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diff --git a/doc/rbd/api/index.rst b/doc/rbd/api/index.rst new file mode 100644 index 000000000..27bb4485d --- /dev/null +++ b/doc/rbd/api/index.rst @@ -0,0 +1,8 @@ +======================== + Ceph Block Device APIs +======================== + +.. toctree:: + :maxdepth: 2 + + librbd (Python) <librbdpy> diff --git a/doc/rbd/api/librbdpy.rst b/doc/rbd/api/librbdpy.rst new file mode 100644 index 000000000..981235f87 --- /dev/null +++ b/doc/rbd/api/librbdpy.rst @@ -0,0 +1,83 @@ +================ + Librbd (Python) +================ + +.. highlight:: python + +The `rbd` python module provides file-like access to RBD images. + + +Example: Creating and writing to an image +========================================= + +To use `rbd`, you must first connect to RADOS and open an IO +context:: + + cluster = rados.Rados(conffile='my_ceph.conf') + cluster.connect() + ioctx = cluster.open_ioctx('mypool') + +Then you instantiate an :class:rbd.RBD object, which you use to create the +image:: + + rbd_inst = rbd.RBD() + size = 4 * 1024**3 # 4 GiB + rbd_inst.create(ioctx, 'myimage', size) + +To perform I/O on the image, you instantiate an :class:rbd.Image object:: + + image = rbd.Image(ioctx, 'myimage') + data = 'foo' * 200 + image.write(data, 0) + +This writes 'foo' to the first 600 bytes of the image. Note that data +cannot be :type:unicode - `Librbd` does not know how to deal with +characters wider than a :c:type:char. + +In the end, you will want to close the image, the IO context and the connection to RADOS:: + + image.close() + ioctx.close() + cluster.shutdown() + +To be safe, each of these calls would need to be in a separate :finally +block:: + + cluster = rados.Rados(conffile='my_ceph_conf') + try: + cluster.connect() + ioctx = cluster.open_ioctx('my_pool') + try: + rbd_inst = rbd.RBD() + size = 4 * 1024**3 # 4 GiB + rbd_inst.create(ioctx, 'myimage', size) + image = rbd.Image(ioctx, 'myimage') + try: + data = 'foo' * 200 + image.write(data, 0) + finally: + image.close() + finally: + ioctx.close() + finally: + cluster.shutdown() + +This can be cumbersome, so the :class:`Rados`, :class:`Ioctx`, and +:class:`Image` classes can be used as context managers that close/shutdown +automatically (see :pep:`343`). Using them as context managers, the +above example becomes:: + + with rados.Rados(conffile='my_ceph.conf') as cluster: + with cluster.open_ioctx('mypool') as ioctx: + rbd_inst = rbd.RBD() + size = 4 * 1024**3 # 4 GiB + rbd_inst.create(ioctx, 'myimage', size) + with rbd.Image(ioctx, 'myimage') as image: + data = 'foo' * 200 + image.write(data, 0) + +API Reference +============= + +.. automodule:: rbd + :members: RBD, Image, SnapIterator diff --git a/doc/rbd/disk.conf b/doc/rbd/disk.conf new file mode 100644 index 000000000..3db9b8a11 --- /dev/null +++ b/doc/rbd/disk.conf @@ -0,0 +1,8 @@ +<disk type='network' device='disk'> + <source protocol='rbd' name='poolname/imagename'> + <host name='{fqdn}' port='6789'/> + <host name='{fqdn}' port='6790'/> + <host name='{fqdn}' port='6791'/> + </source> + <target dev='vda' bus='virtio'/> +</disk> diff --git a/doc/rbd/index.rst b/doc/rbd/index.rst new file mode 100644 index 000000000..4a8029bba --- /dev/null +++ b/doc/rbd/index.rst @@ -0,0 +1,72 @@ +=================== + Ceph Block Device +=================== + +.. index:: Ceph Block Device; introduction + +A block is a sequence of bytes (often 512). +Block-based storage interfaces are a mature and common way to store data on +media including HDDs, SSDs, CDs, floppy disks, and even tape. +The ubiquity of block device interfaces is a perfect fit for interacting +with mass data storage including Ceph. + +Ceph block devices are thin-provisioned, resizable, and store data striped over +multiple OSDs. Ceph block devices leverage +:abbr:`RADOS (Reliable Autonomic Distributed Object Store)` capabilities +including snapshotting, replication and strong consistency. Ceph block +storage clients communicate with Ceph clusters through kernel modules or +the ``librbd`` library. + +.. ditaa:: + + +------------------------+ +------------------------+ + | Kernel Module | | librbd | + +------------------------+-+------------------------+ + | RADOS Protocol | + +------------------------+-+------------------------+ + | OSDs | | Monitors | + +------------------------+ +------------------------+ + +.. note:: Kernel modules can use Linux page caching. For ``librbd``-based + applications, Ceph supports `RBD Caching`_. + +Ceph's block devices deliver high performance with vast scalability to +`kernel modules`_, or to :abbr:`KVMs (kernel virtual machines)` such as `QEMU`_, and +cloud-based computing systems like `OpenStack`_ and `CloudStack`_ that rely on +libvirt and QEMU to integrate with Ceph block devices. You can use the same cluster +to operate the :ref:`Ceph RADOS Gateway <object-gateway>`, the +:ref:`Ceph File System <ceph-file-system>`, and Ceph block devices simultaneously. + +.. important:: To use Ceph Block Devices, you must have access to a running + Ceph cluster. + +.. toctree:: + :maxdepth: 1 + + Basic Commands <rados-rbd-cmds> + +.. toctree:: + :maxdepth: 2 + + Operations <rbd-operations> + +.. toctree:: + :maxdepth: 2 + + Integrations <rbd-integrations> + +.. toctree:: + :maxdepth: 2 + + Manpages <man/index> + +.. toctree:: + :maxdepth: 2 + + APIs <api/index> + +.. _RBD Caching: ./rbd-config-ref/ +.. _kernel modules: ./rbd-ko/ +.. _QEMU: ./qemu-rbd/ +.. _OpenStack: ./rbd-openstack +.. _CloudStack: ./rbd-cloudstack diff --git a/doc/rbd/iscsi-initiator-esx.rst b/doc/rbd/iscsi-initiator-esx.rst new file mode 100644 index 000000000..8bed6f2a2 --- /dev/null +++ b/doc/rbd/iscsi-initiator-esx.rst @@ -0,0 +1,105 @@ +------------------------------ +iSCSI Initiator for VMware ESX +------------------------------ + +**Prerequisite:** + +- VMware ESX 6.5 or later using Virtual Machine compatibility 6.5 with VMFS 6. + +**iSCSI Discovery and Multipath Device Setup:** + +The following instructions will use the default vSphere web client and esxcli. + +#. Enable Software iSCSI + + .. image:: ../images/esx_web_client_storage_main.png + :align: center + + Click on "Storage" from "Navigator", and select the "Adapters" tab. + From there right click "Configure iSCSI". + +#. Set Initiator Name + + .. image:: ../images/esx_config_iscsi_main.png + :align: center + + If the initiator name in the "Name & alias" section is not the same name + used when creating the client during gwcli setup or the initiator name used + in the ansible client_connections client variable, then ssh to the ESX + host and run the following esxcli commands to change the name. + + Get the adapter name for Software iSCSI: + + :: + + > esxcli iscsi adapter list + > Adapter Driver State UID Description + > ------- --------- ------ ------------- ---------------------- + > vmhba64 iscsi_vmk online iscsi.vmhba64 iSCSI Software Adapter + + In this example the software iSCSI adapter is vmhba64 and the initiator + name is iqn.1994-05.com.redhat:rh7-client: + + :: + + > esxcli iscsi adapter set -A vmhba64 -n iqn.1994-05.com.redhat:rh7-client + +#. Setup CHAP + + .. image:: ../images/esx_chap.png + :align: center + + Expand the CHAP authentication section, select "Do not use CHAP unless + required by target" and enter the CHAP credentials used in the gwcli + auth command or ansible client_connections credentials variable. + + The Mutual CHAP authentication section should have "Do not use CHAP" + selected. + + Warning: There is a bug in the web client where the requested CHAP + settings are not always used initially. On the iSCSI gateway kernel + logs you will see the error: + + :: + + > kernel: CHAP user or password not set for Initiator ACL + > kernel: Security negotiation failed. + > kernel: iSCSI Login negotiation failed. + + To workaround this set the CHAP settings with the esxcli command. Here + authname is the username and secret is the password used in previous + examples: + + :: + + > esxcli iscsi adapter auth chap set --direction=uni --authname=myiscsiusername --secret=myiscsipassword --level=discouraged -A vmhba64 + +#. Configure iSCSI Settings + + .. image:: ../images/esx_iscsi_recov_timeout.png + :align: center + + Expand Advanced settings and set the "RecoveryTimeout" to 25. + +#. Set the discovery address + + .. image:: ../images/esx_config_iscsi_main.png + :align: center + + In the Dynamic targets section, click "Add dynamic target" and under + Addresses add one of the gateway IP addresses added during the iSCSI + gateway setup stage in the gwcli section or an IP set in the ansible + gateway_ip_list variable. Only one address needs to be added as the gateways + have been setup so all the iSCSI portals are returned during discovery. + + Finally, click the "Save configuration" button. In the Devices tab, you + should see the RBD image. + + The LUN should be automatically configured and using the ALUA SATP and + MRU PSP. Other SATPs and PSPs must not be used. This can be verified with + the esxcli command: + + :: + + > esxcli storage nmp path list -d eui.your_devices_id + diff --git a/doc/rbd/iscsi-initiator-linux.rst b/doc/rbd/iscsi-initiator-linux.rst new file mode 100644 index 000000000..ba374c40c --- /dev/null +++ b/doc/rbd/iscsi-initiator-linux.rst @@ -0,0 +1,91 @@ +------------------------- +iSCSI Initiator for Linux +------------------------- + +**Prerequisite:** + +- Package ``iscsi-initiator-utils`` + +- Package ``device-mapper-multipath`` + +**Installing:** + +Install the iSCSI initiator and multipath tools: + + :: + + # yum install iscsi-initiator-utils + # yum install device-mapper-multipath + +**Configuring:** + +#. Create the default ``/etc/multipath.conf`` file and enable the + ``multipathd`` service: + + :: + + # mpathconf --enable --with_multipathd y + +#. Add the following to ``/etc/multipath.conf`` file: + + :: + + devices { + device { + vendor "LIO-ORG" + hardware_handler "1 alua" + path_grouping_policy "failover" + path_selector "queue-length 0" + failback 60 + path_checker tur + prio alua + prio_args exclusive_pref_bit + fast_io_fail_tmo 25 + no_path_retry queue + } + } + +#. Restart the ``multipathd`` service: + + :: + + # systemctl reload multipathd + +**iSCSI Discovery and Setup:** + +#. If CHAP was setup on the iSCSI gateway, provide a CHAP username and + password by updating the ``/etc/iscsi/iscsid.conf`` file accordingly. + +#. Discover the target portals: + + :: + + # iscsiadm -m discovery -t st -p 192.168.56.101 + 192.168.56.101:3260,1 iqn.2003-01.org.linux-iscsi.rheln1 + 192.168.56.102:3260,2 iqn.2003-01.org.linux-iscsi.rheln1 + +#. Login to target: + + :: + + # iscsiadm -m node -T iqn.2003-01.org.linux-iscsi.rheln1 -l + +**Multipath IO Setup:** + +The multipath daemon (``multipathd``), will set up devices automatically +based on the ``multipath.conf`` settings. Running the ``multipath`` +command show devices setup in a failover configuration with a priority +group for each path. + +:: + + # multipath -ll + mpathbt (360014059ca317516a69465c883a29603) dm-1 LIO-ORG ,IBLOCK + size=1.0G features='0' hwhandler='1 alua' wp=rw + |-+- policy='queue-length 0' prio=50 status=active + | `- 28:0:0:1 sde 8:64 active ready running + `-+- policy='queue-length 0' prio=10 status=enabled + `- 29:0:0:1 sdc 8:32 active ready running + +You should now be able to use the RBD image like you would a normal +multipath’d iSCSI disk. diff --git a/doc/rbd/iscsi-initiator-win.rst b/doc/rbd/iscsi-initiator-win.rst new file mode 100644 index 000000000..e76b03d18 --- /dev/null +++ b/doc/rbd/iscsi-initiator-win.rst @@ -0,0 +1,102 @@ +------------------------------------- +iSCSI Initiator for Microsoft Windows +------------------------------------- + +**Prerequisite:** + +- Microsoft Windows Server 2016 or later + +**iSCSI Initiator, Discovery and Setup:** + +#. Install the iSCSI initiator driver and MPIO tools. + +#. Launch the MPIO program, click on the "Discover Multi-Paths" tab, check the + "Add support for iSCSI devices” box, and click "Add". This will require a + reboot. + +#. On the iSCSI Initiator Properties window, on the "Discovery" tab, add a target + portal. Enter the IP address or DNS name and Port of the Ceph iSCSI gateway. + +#. On the “Targets” tab, select the target and click on “Connect”. + +#. On the “Connect To Target” window, select the “Enable multi-path” option, and + click the “Advanced” button. + +#. Under the "Connet using" section, select a “Target portal IP” . Select the + “Enable CHAP login on” and enter the "Name" and "Target secret" values from the + Ceph iSCSI Ansible client credentials section, and click OK. + +#. Repeat steps 5 and 6 for each target portal defined when setting up + the iSCSI gateway. + +**Multipath IO Setup:** + +Configuring the MPIO load balancing policy, setting the timeout and +retry options are using PowerShell with the ``mpclaim`` command. The +rest is done in the iSCSI Initiator tool. + +.. note:: + It is recommended to increase the ``PDORemovePeriod`` option to 120 + seconds from PowerShell. This value might need to be adjusted based + on the application. When all paths are down, and 120 seconds + expires, the operating system will start failing IO requests. + +:: + + Set-MPIOSetting -NewPDORemovePeriod 120 + +:: + + mpclaim.exe -l -m 1 + +:: + + mpclaim -s -m + MSDSM-wide Load Balance Policy: Fail Over Only + +#. Using the iSCSI Initiator tool, from the “Targets” tab, click on + the “Devices...” button. + +#. From the Devices window, select a disk and click the + “MPIO...” button. + +#. On the "Device Details" window the paths to each target portal is + displayed. If using the ``ceph-ansible`` setup method, the + iSCSI gateway will use ALUA to tell the iSCSI initiator which path + and iSCSI gateway should be used as the primary path. The Load + Balancing Policy “Fail Over Only” must be selected + +:: + + mpclaim -s -d $MPIO_DISK_ID + +.. note:: + For the ``ceph-ansible`` setup method, there will be one + Active/Optimized path which is the path to the iSCSI gateway node + that owns the LUN, and there will be an Active/Unoptimized path for + each other iSCSI gateway node. + +**Tuning:** + +Consider using the following registry settings: + +- Windows Disk Timeout + + :: + + HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk + + :: + + TimeOutValue = 65 + +- Microsoft iSCSI Initiator Driver + + :: + + HKEY_LOCAL_MACHINE\\SYSTEM\CurrentControlSet\Control\Class\{4D36E97B-E325-11CE-BFC1-08002BE10318}\<Instance_Number>\Parameters + + :: + + LinkDownTime = 25 + SRBTimeoutDelta = 15 diff --git a/doc/rbd/iscsi-initiators.rst b/doc/rbd/iscsi-initiators.rst new file mode 100644 index 000000000..67447789d --- /dev/null +++ b/doc/rbd/iscsi-initiators.rst @@ -0,0 +1,23 @@ +-------------------------------- +Configuring the iSCSI Initiators +-------------------------------- + +- `iSCSI Initiator for Linux <../iscsi-initiator-linux>`_ + +- `iSCSI Initiator for Microsoft Windows <../iscsi-initiator-win>`_ + +- `iSCSI Initiator for VMware ESX <../iscsi-initiator-esx>`_ + + .. warning:: + + Applications that use SCSI persistent group reservations (PGR) and + SCSI 2 based reservations are not supported when exporting a RBD image + through more than one iSCSI gateway. + +.. toctree:: + :maxdepth: 1 + :hidden: + + Linux <iscsi-initiator-linux> + Microsoft Windows <iscsi-initiator-win> + VMware ESX <iscsi-initiator-esx> diff --git a/doc/rbd/iscsi-monitoring.rst b/doc/rbd/iscsi-monitoring.rst new file mode 100644 index 000000000..da94bad87 --- /dev/null +++ b/doc/rbd/iscsi-monitoring.rst @@ -0,0 +1,85 @@ +------------------------------ +Monitoring Ceph iSCSI gateways +------------------------------ + +Ceph provides a tool for iSCSI gateway environments +to monitor performance of exported RADOS Block Device (RBD) images. + +The ``gwtop`` tool is a ``top``-like tool that displays aggregated +performance metrics of RBD images that are exported to clients over +iSCSI. The metrics are sourced from a Performance Metrics Domain Agent +(PMDA). Information from the Linux-IO target (LIO) PMDA is used to list +each exported RBD image, the connected client, and its associated I/O +metrics. + +**Requirements:** + +- A running Ceph iSCSI gateway + +**Installing:** + +#. As ``root``, install the ``ceph-iscsi-tools`` package on each iSCSI + gateway node: + + :: + + # yum install ceph-iscsi-tools + +#. As ``root``, install the performance co-pilot package on each iSCSI + gateway node: + + :: + + # yum install pcp + +#. As ``root``, install the LIO PMDA package on each iSCSI gateway node: + + :: + + # yum install pcp-pmda-lio + +#. As ``root``, enable and start the performance co-pilot service on + each iSCSI gateway node: + + :: + + # systemctl enable pmcd + # systemctl start pmcd + +#. As ``root``, register the ``pcp-pmda-lio`` agent: + + :: + + cd /var/lib/pcp/pmdas/lio + ./Install + +By default, ``gwtop`` assumes the iSCSI gateway configuration object is +stored in a RADOS object called ``gateway.conf`` in the ``rbd`` pool. +This configuration defines the iSCSI gateways to contact for gathering +the performance statistics. This can be overridden by using either the +``-g`` or ``-c`` flags. See ``gwtop --help`` for more details. + +The LIO configuration determines which type of performance statistics to +extract from performance co-pilot. When ``gwtop`` starts it looks at the +LIO configuration, and if it find user-space disks, then ``gwtop`` +selects the LIO collector automatically. + +**Example ``gwtop`` Outputs** + +:: + + gwtop 2/2 Gateways CPU% MIN: 4 MAX: 5 Network Total In: 2M Out: 3M 10:20:00 + Capacity: 8G Disks: 8 IOPS: 503 Clients: 1 Ceph: HEALTH_OK OSDs: 3 + Pool.Image Src Size iops rMB/s wMB/s Client + iscsi.t1703 500M 0 0.00 0.00 + iscsi.testme1 500M 0 0.00 0.00 + iscsi.testme2 500M 0 0.00 0.00 + iscsi.testme3 500M 0 0.00 0.00 + iscsi.testme5 500M 0 0.00 0.00 + rbd.myhost_1 T 4G 504 1.95 0.00 rh460p(CON) + rbd.test_2 1G 0 0.00 0.00 + rbd.testme 500M 0 0.00 0.00 + +In the *Client* column, ``(CON)`` means the iSCSI initiator (client) is +currently logged into the iSCSI gateway. If ``-multi-`` is displayed, +then multiple clients are mapped to the single RBD image. diff --git a/doc/rbd/iscsi-overview.rst b/doc/rbd/iscsi-overview.rst new file mode 100644 index 000000000..879083c3f --- /dev/null +++ b/doc/rbd/iscsi-overview.rst @@ -0,0 +1,57 @@ +.. _ceph-iscsi: + +================== +Ceph iSCSI Gateway +================== + +The iSCSI Gateway presents a Highly Available (HA) iSCSI target that exports +RADOS Block Device (RBD) images as SCSI disks. The iSCSI protocol allows +clients (initiators) to send SCSI commands to storage devices (targets) over a +TCP/IP network, enabling clients without native Ceph client support to access +Ceph block storage. + +Each iSCSI gateway exploits the Linux IO target kernel subsystem (LIO) to +provide iSCSI protocol support. LIO utilizes userspace passthrough (TCMU) to +interact with Ceph's librbd library and expose RBD images to iSCSI clients. +With Ceph’s iSCSI gateway you can provision a fully integrated block-storage +infrastructure with all the features and benefits of a conventional Storage +Area Network (SAN). + +.. ditaa:: + Cluster Network (optional) + +-------------------------------------------+ + | | | | + +-------+ +-------+ +-------+ +-------+ + | | | | | | | | + | OSD 1 | | OSD 2 | | OSD 3 | | OSD N | + | {s}| | {s}| | {s}| | {s}| + +-------+ +-------+ +-------+ +-------+ + | | | | + +--------->| | +---------+ | |<---------+ + : | | | RBD | | | : + | +----------------| Image |----------------+ | + | Public Network | {d} | | + | +---------+ | + | | + | +-------------------+ | + | +--------------+ | iSCSI Initiators | +--------------+ | + | | iSCSI GW | | +-----------+ | | iSCSI GW | | + +-->| RBD Module |<--+ | Various | +-->| RBD Module |<--+ + | | | | Operating | | | | + +--------------+ | | Systems | | +--------------+ + | +-----------+ | + +-------------------+ + +.. warning:: + + The iSCSI gateway is in maintenance as of November 2022. This means that + it is no longer in active development and will not be updated to add + new features. + +.. toctree:: + :maxdepth: 1 + + Requirements <iscsi-requirements> + Configuring the iSCSI Target <iscsi-targets> + Configuring the iSCSI Initiators <iscsi-initiators> + Monitoring the iSCSI Gateways <iscsi-monitoring> diff --git a/doc/rbd/iscsi-requirements.rst b/doc/rbd/iscsi-requirements.rst new file mode 100644 index 000000000..50dfc2a27 --- /dev/null +++ b/doc/rbd/iscsi-requirements.rst @@ -0,0 +1,51 @@ +========================== +iSCSI Gateway Requirements +========================== + +It is recommended to provision two to four iSCSI gateway nodes to +realize a highly available Ceph iSCSI gateway solution. + +For hardware recommendations, see :ref:`hardware-recommendations` . + +.. note:: + On iSCSI gateway nodes the memory footprint is a function of + of the RBD images mapped and can grow to be large. Plan memory + requirements accordingly based on the number RBD images to be mapped. + +There are no specific iSCSI gateway options for the Ceph Monitors or +OSDs, but it is important to lower the default heartbeat interval for +detecting down OSDs to reduce the possibility of initiator timeouts. +The following configuration options are suggested:: + + [osd] + osd heartbeat grace = 20 + osd heartbeat interval = 5 + +- Updating Running State From a Ceph Monitor Node + + :: + + ceph tell <daemon_type>.<id> config set <parameter_name> <new_value> + + :: + + ceph tell osd.* config set osd_heartbeat_grace 20 + ceph tell osd.* config set osd_heartbeat_interval 5 + +- Updating Running State On Each OSD Node + + :: + + ceph daemon <daemon_type>.<id> config set osd_client_watch_timeout 15 + + :: + + ceph daemon osd.0 config set osd_heartbeat_grace 20 + ceph daemon osd.0 config set osd_heartbeat_interval 5 + +For more details on setting Ceph's configuration options, see +:ref:`configuring-ceph`. Be sure to persist these settings in +``/etc/ceph.conf`` or, on Mimic and later releases, in the +centralized config store. + + diff --git a/doc/rbd/iscsi-target-ansible.rst b/doc/rbd/iscsi-target-ansible.rst new file mode 100644 index 000000000..d38e3bd01 --- /dev/null +++ b/doc/rbd/iscsi-target-ansible.rst @@ -0,0 +1,234 @@ +========================================== +Configuring the iSCSI Target using Ansible +========================================== + +The Ceph iSCSI gateway is the iSCSI target node and also a Ceph client +node. The Ceph iSCSI gateway can be provisioned on dedicated node +or be colocated on a Ceph Object Store Disk (OSD) node. The following steps will +install and configure the Ceph iSCSI gateway for basic operation. + +**Requirements:** + +- A running Ceph Luminous (12.2.x) cluster or newer + +- Red Hat Enterprise Linux/CentOS 7.5 (or newer); Linux kernel v4.16 (or newer) + +- The ``ceph-iscsi`` package installed on all the iSCSI gateway nodes + +**Installation:** + +#. On the Ansible installer node, which could be either the administration node + or a dedicated deployment node, perform the following steps: + + #. As ``root``, install the ``ceph-ansible`` package: + + :: + + # yum install ceph-ansible + + #. Add an entry in ``/etc/ansible/hosts`` file for the gateway group: + + :: + + [iscsigws] + ceph-igw-1 + ceph-igw-2 + +.. note:: + If co-locating the iSCSI gateway with an OSD node, then add the OSD node to the + ``[iscsigws]`` section. + +**Configuration:** + +The ``ceph-ansible`` package places a file in the ``/usr/share/ceph-ansible/group_vars/`` +directory called ``iscsigws.yml.sample``. Create a copy of this sample file named +``iscsigws.yml``. Review the following Ansible variables and descriptions, +and update accordingly. See the ``iscsigws.yml.sample`` for a full list of +advanced variables. + ++--------------------------------------+--------------------------------------+ +| Variable | Meaning/Purpose | ++======================================+======================================+ +| ``seed_monitor`` | Each gateway needs access to the | +| | ceph cluster for rados and rbd | +| | calls. This means the iSCSI gateway | +| | must have an appropriate | +| | ``/etc/ceph/`` directory defined. | +| | The ``seed_monitor`` host is used to | +| | populate the iSCSI gateway’s | +| | ``/etc/ceph/`` directory. | ++--------------------------------------+--------------------------------------+ +| ``cluster_name`` | Define a custom storage cluster | +| | name. | ++--------------------------------------+--------------------------------------+ +| ``gateway_keyring`` | Define a custom keyring name. | ++--------------------------------------+--------------------------------------+ +| ``deploy_settings`` | If set to ``true``, then deploy the | +| | settings when the playbook is ran. | ++--------------------------------------+--------------------------------------+ +| ``perform_system_checks`` | This is a boolean value that checks | +| | for multipath and lvm configuration | +| | settings on each gateway. It must be | +| | set to true for at least the first | +| | run to ensure multipathd and lvm are | +| | configured properly. | ++--------------------------------------+--------------------------------------+ +| ``api_user`` | The user name for the API. The | +| | default is `admin`. | ++--------------------------------------+--------------------------------------+ +| ``api_password`` | The password for using the API. The | +| | default is `admin`. | ++--------------------------------------+--------------------------------------+ +| ``api_port`` | The TCP port number for using the | +| | API. The default is `5000`. | ++--------------------------------------+--------------------------------------+ +| ``api_secure`` | True if TLS must be used. The | +| | default is `false`. If true the user | +| | must create the necessary | +| | certificate and key files. See the | +| | gwcli man file for details. | ++--------------------------------------+--------------------------------------+ +| ``trusted_ip_list`` | A list of IPv4 or IPv6 addresses | +| | who have access to the API. By | +| | default, only the iSCSI gateway | +| | nodes have access. | ++--------------------------------------+--------------------------------------+ + +**Deployment:** + +Perform the followint steps on the Ansible installer node. + +#. As ``root``, execute the Ansible playbook: + + :: + + # cd /usr/share/ceph-ansible + # ansible-playbook site.yml --limit iscsigws + + .. note:: + The Ansible playbook will handle RPM dependencies, setting up daemons, + and installing gwcli so it can be used to create iSCSI targets and export + RBD images as LUNs. In past versions, ``iscsigws.yml`` could define the + iSCSI target and other objects like clients, images and LUNs, but this is + no longer supported. + +#. Verify the configuration from an iSCSI gateway node: + + :: + + # gwcli ls + + .. note:: + See the `Configuring the iSCSI Target using the Command Line Interface`_ + section to create gateways, LUNs, and clients using the `gwcli` tool. + + .. important:: + Attempting to use the ``targetcli`` tool to change the configuration will + cause problems including ALUA misconfiguration and path failover + issues. There is the potential to corrupt data, to have mismatched + configuration across iSCSI gateways, and to have mismatched WWN information, + leading to client multipath problems. + +**Service Management:** + +The ``ceph-iscsi`` package installs the configuration management +logic and a Systemd service called ``rbd-target-api``. When the Systemd +service is enabled, the ``rbd-target-api`` will start at boot time and +will restore the Linux IO state. The Ansible playbook disables the +target service during the deployment. Below are the outcomes of when +interacting with the ``rbd-target-api`` Systemd service. + +:: + + # systemctl <start|stop|restart|reload> rbd-target-api + +- ``reload`` + + A reload request will force ``rbd-target-api`` to reread the + configuration and apply it to the current running environment. This + is normally not required, since changes are deployed in parallel from + Ansible to all iSCSI gateway nodes + +- ``stop`` + + A stop request will close the gateway’s portal interfaces, dropping + connections to clients and wipe the current LIO configuration from + the kernel. This returns the iSCSI gateway to a clean state. When + clients are disconnected, active I/O is rescheduled to the other + iSCSI gateways by the client side multipathing layer. + +**Removing the Configuration:** + +The ``ceph-ansible`` package provides an Ansible playbook to +remove the iSCSI gateway configuration and related RBD images. The +Ansible playbook is ``/usr/share/ceph-ansible/purge_gateways.yml``. When +this Ansible playbook is ran a prompted for the type of purge to +perform: + +*lio* : + +In this mode the LIO configuration is purged on all iSCSI gateways that +are defined. Disks that were created are left untouched within the Ceph +storage cluster. + +*all* : + +When ``all`` is chosen, the LIO configuration is removed together with +**all** RBD images that were defined within the iSCSI gateway +environment, other unrelated RBD images will not be removed. Ensure the +correct mode is chosen, this operation will delete data. + +.. warning:: + A purge operation is destructive action against your iSCSI gateway + environment. + +.. warning:: + A purge operation will fail, if RBD images have snapshots or clones + and are exported through the Ceph iSCSI gateway. + +:: + + [root@rh7-iscsi-client ceph-ansible]# ansible-playbook purge_gateways.yml + Which configuration elements should be purged? (all, lio or abort) [abort]: all + + + PLAY [Confirm removal of the iSCSI gateway configuration] ********************* + + + GATHERING FACTS *************************************************************** + ok: [localhost] + + + TASK: [Exit playbook if user aborted the purge] ******************************* + skipping: [localhost] + + + TASK: [set_fact ] ************************************************************* + ok: [localhost] + + + PLAY [Removing the gateway configuration] ************************************* + + + GATHERING FACTS *************************************************************** + ok: [ceph-igw-1] + ok: [ceph-igw-2] + + + TASK: [igw_purge | purging the gateway configuration] ************************* + changed: [ceph-igw-1] + changed: [ceph-igw-2] + + + TASK: [igw_purge | deleting configured rbd devices] *************************** + changed: [ceph-igw-1] + changed: [ceph-igw-2] + + + PLAY RECAP ******************************************************************** + ceph-igw-1 : ok=3 changed=2 unreachable=0 failed=0 + ceph-igw-2 : ok=3 changed=2 unreachable=0 failed=0 + localhost : ok=2 changed=0 unreachable=0 failed=0 + + +.. _Configuring the iSCSI Target using the Command Line Interface: ../iscsi-target-cli diff --git a/doc/rbd/iscsi-target-cli-manual-install.rst b/doc/rbd/iscsi-target-cli-manual-install.rst new file mode 100644 index 000000000..ccc422e0d --- /dev/null +++ b/doc/rbd/iscsi-target-cli-manual-install.rst @@ -0,0 +1,190 @@ +============================== +Manual ceph-iscsi Installation +============================== + +**Requirements** + +To complete the installation of ceph-iscsi, there are 4 steps: + +1. Install common packages from your Linux distribution's software repository +2. Install Git to fetch the remaining packages directly from their Git repositories +3. Ensure a compatible kernel is used +4. Install all the components of ceph-iscsi and start associated daemons: + + - tcmu-runner + - rtslib-fb + - configshell-fb + - targetcli-fb + - ceph-iscsi + + +1. Install Common Packages +========================== + +The following packages will be used by ceph-iscsi and target tools. +They must be installed from your Linux distribution's software repository +on each machine that will be a iSCSI gateway: + +- libnl3 +- libkmod +- librbd1 +- pyparsing +- python kmod +- python pyudev +- python gobject +- python urwid +- python pyparsing +- python rados +- python rbd +- python netifaces +- python crypto +- python requests +- python flask +- pyOpenSSL + + +2. Install Git +============== + +In order to install all the packages needed to run iSCSI with Ceph, you need to download them directly from their repository by using Git. +On CentOS/RHEL execute: + +:: + + > sudo yum install git + +On Debian/Ubuntu execute: + +:: + + > sudo apt install git + +To know more about Git and how it works, please, visit https://git-scm.com + + +3. Ensure a compatible kernel is used +===================================== + +Ensure you use a supported kernel that contains the required Ceph iSCSI patches: + +- all Linux distribution with a kernel v4.16 or newer, or +- Red Hat Enterprise Linux or CentOS 7.5 or later (in these distributions ceph-iscsi support is backported) + +If you are already using a compatible kernel, you can go to next step. +However, if you are NOT using a compatible kernel then check your distro's +documentation for specific instructions on how to build this kernel. The only +Ceph iSCSI specific requirements are that the following build options must be +enabled: + + :: + + CONFIG_TARGET_CORE=m + CONFIG_TCM_USER2=m + CONFIG_ISCSI_TARGET=m + + +4. Install ceph-iscsi +======================================================== + +Finally, the remaining tools can be fetched directly from their Git repositories and their associated services started + + +tcmu-runner +----------- + + Installation: + + :: + + > git clone https://github.com/open-iscsi/tcmu-runner + > cd tcmu-runner + + Run the following command to install all the needed dependencies: + + :: + + > ./extra/install_dep.sh + + Now you can build the tcmu-runner. + To do so, use the following build command: + + :: + + > cmake -Dwith-glfs=false -Dwith-qcow=false -DSUPPORT_SYSTEMD=ON -DCMAKE_INSTALL_PREFIX=/usr + > make install + + Enable and start the daemon: + + :: + + > systemctl daemon-reload + > systemctl enable tcmu-runner + > systemctl start tcmu-runner + + +rtslib-fb +--------- + + Installation: + + :: + + > git clone https://github.com/open-iscsi/rtslib-fb.git + > cd rtslib-fb + > python setup.py install + +configshell-fb +-------------- + + Installation: + + :: + + > git clone https://github.com/open-iscsi/configshell-fb.git + > cd configshell-fb + > python setup.py install + +targetcli-fb +------------ + + Installation: + + :: + + > git clone https://github.com/open-iscsi/targetcli-fb.git + > cd targetcli-fb + > python setup.py install + > mkdir /etc/target + > mkdir /var/target + + .. warning:: The ceph-iscsi tools assume they are managing all targets + on the system. If targets have been setup and are being managed by + targetcli the target service must be disabled. + +ceph-iscsi +----------------- + + Installation: + + :: + + > git clone https://github.com/ceph/ceph-iscsi.git + > cd ceph-iscsi + > python setup.py install --install-scripts=/usr/bin + > cp usr/lib/systemd/system/rbd-target-gw.service /lib/systemd/system + > cp usr/lib/systemd/system/rbd-target-api.service /lib/systemd/system + + Enable and start the daemon: + + :: + + > systemctl daemon-reload + > systemctl enable rbd-target-gw + > systemctl start rbd-target-gw + > systemctl enable rbd-target-api + > systemctl start rbd-target-api + +Installation is complete. Proceed to the setup section in the +`main ceph-iscsi CLI page`_. + +.. _`main ceph-iscsi CLI page`: ../iscsi-target-cli diff --git a/doc/rbd/iscsi-target-cli.rst b/doc/rbd/iscsi-target-cli.rst new file mode 100644 index 000000000..d888a34b0 --- /dev/null +++ b/doc/rbd/iscsi-target-cli.rst @@ -0,0 +1,244 @@ +============================================================= +Configuring the iSCSI Target using the Command Line Interface +============================================================= + +The Ceph iSCSI gateway is both an iSCSI target and a Ceph client; +think of it as a "translator" between Ceph's RBD interface +and the iSCSI standard. The Ceph iSCSI gateway can run on a +standalone node or be colocated with other daemons eg. on +a Ceph Object Store Disk (OSD) node. When co-locating, ensure +that sufficient CPU and memory are available to share. +The following steps install and configure the Ceph iSCSI gateway for basic operation. + +**Requirements:** + +- A running Ceph Luminous or later storage cluster + +- Red Hat Enterprise Linux/CentOS 7.5 (or newer); Linux kernel v4.16 (or newer) + +- The following packages must be installed from your Linux distribution's software repository: + + - ``targetcli-2.1.fb47`` or newer package + + - ``python-rtslib-2.1.fb68`` or newer package + + - ``tcmu-runner-1.4.0`` or newer package + + - ``ceph-iscsi-3.2`` or newer package + + .. important:: + If previous versions of these packages exist, then they must + be removed first before installing the newer versions. + +Do the following steps on the Ceph iSCSI gateway node before proceeding +to the *Installing* section: + +#. If the Ceph iSCSI gateway is not colocated on an OSD node, then copy + the Ceph configuration files, located in ``/etc/ceph/``, from a + running Ceph node in the storage cluster to the iSCSI Gateway node. + The Ceph configuration files must exist on the iSCSI gateway node + under ``/etc/ceph/``. + +#. Install and configure the `Ceph Command-line Interface`_ + +#. If needed, open TCP ports 3260 and 5000 on the firewall. + + .. note:: + Access to port 5000 should be restricted to a trusted internal network or + only the individual hosts where ``gwcli`` is used or ``ceph-mgr`` daemons + are running. + +#. Create a new or use an existing RADOS Block Device (RBD). + +**Installing:** + +If you are using the upstream ceph-iscsi package follow the +`manual install instructions`_. + +.. _`manual install instructions`: ../iscsi-target-cli-manual-install + +.. toctree:: + :hidden: + + iscsi-target-cli-manual-install + +For rpm based instructions execute the following commands: + +#. As ``root``, on all iSCSI gateway nodes, install the + ``ceph-iscsi`` package: + + :: + + # yum install ceph-iscsi + +#. As ``root``, on all iSCSI gateway nodes, install the ``tcmu-runner`` + package: + + :: + + # yum install tcmu-runner + +**Setup:** + +#. gwcli requires a pool with the name ``rbd``, so it can store metadata + like the iSCSI configuration. To check if this pool has been created + run: + + :: + + # ceph osd lspools + + If it does not exist instructions for creating pools can be found on the + `RADOS pool operations page + <http://docs.ceph.com/en/latest/rados/operations/pools/>`_. + +#. As ``root``, on a iSCSI gateway node, create a file named + ``iscsi-gateway.cfg`` in the ``/etc/ceph/`` directory: + + :: + + # touch /etc/ceph/iscsi-gateway.cfg + + #. Edit the ``iscsi-gateway.cfg`` file and add the following lines: + + :: + + [config] + # Name of the Ceph storage cluster. A suitable Ceph configuration file allowing + # access to the Ceph storage cluster from the gateway node is required, if not + # colocated on an OSD node. + cluster_name = ceph + + # Place a copy of the ceph cluster's admin keyring in the gateway's /etc/ceph + # drectory and reference the filename here + gateway_keyring = ceph.client.admin.keyring + + + # API settings. + # The API supports a number of options that allow you to tailor it to your + # local environment. If you want to run the API under https, you will need to + # create cert/key files that are compatible for each iSCSI gateway node, that is + # not locked to a specific node. SSL cert and key files *must* be called + # 'iscsi-gateway.crt' and 'iscsi-gateway.key' and placed in the '/etc/ceph/' directory + # on *each* gateway node. With the SSL files in place, you can use 'api_secure = true' + # to switch to https mode. + + # To support the API, the bare minimum settings are: + api_secure = false + + # Additional API configuration options are as follows, defaults shown. + # api_user = admin + # api_password = admin + # api_port = 5001 + # trusted_ip_list = 192.168.0.10,192.168.0.11 + + .. note:: + trusted_ip_list is a list of IP addresses on each iSCSI gateway that + will be used for management operations like target creation, LUN + exporting, etc. The IP can be the same that will be used for iSCSI + data, like READ/WRITE commands to/from the RBD image, but using + separate IPs is recommended. + + .. important:: + The ``iscsi-gateway.cfg`` file must be identical on all iSCSI gateway nodes. + + #. As ``root``, copy the ``iscsi-gateway.cfg`` file to all iSCSI + gateway nodes. + +#. As ``root``, on all iSCSI gateway nodes, enable and start the API + service: + + :: + + # systemctl daemon-reload + + # systemctl enable rbd-target-gw + # systemctl start rbd-target-gw + + # systemctl enable rbd-target-api + # systemctl start rbd-target-api + + +**Configuring:** + +gwcli will create and configure the iSCSI target and RBD images and copy the +configuration across the gateways setup in the last section. Lower level +tools including targetcli and rbd can be used to query the local configuration, +but should not be used to modify it. This next section will demonstrate how +to create a iSCSI target and export a RBD image as LUN 0. + +#. As ``root``, on a iSCSI gateway node, start the iSCSI gateway + command-line interface: + + :: + + # gwcli + +#. Go to iscsi-targets and create a target with the name + iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw: + + :: + + > /> cd /iscsi-target + > /iscsi-target> create iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw + +#. Create the iSCSI gateways. The IPs used below are the ones that will be + used for iSCSI data like READ and WRITE commands. They can be the + same IPs used for management operations listed in trusted_ip_list, + but it is recommended that different IPs are used. + + :: + + > /iscsi-target> cd iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw/gateways + > /iscsi-target...-igw/gateways> create ceph-gw-1 10.172.19.21 + > /iscsi-target...-igw/gateways> create ceph-gw-2 10.172.19.22 + + If not using RHEL/CentOS or using an upstream or ceph-iscsi-test kernel, + the skipchecks=true argument must be used. This will avoid the Red Hat kernel + and rpm checks: + + :: + + > /iscsi-target> cd iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw/gateways + > /iscsi-target...-igw/gateways> create ceph-gw-1 10.172.19.21 skipchecks=true + > /iscsi-target...-igw/gateways> create ceph-gw-2 10.172.19.22 skipchecks=true + +#. Add a RBD image with the name disk_1 in the pool rbd: + + :: + + > /iscsi-target...-igw/gateways> cd /disks + > /disks> create pool=rbd image=disk_1 size=90G + +#. Create a client with the initiator name iqn.1994-05.com.redhat:rh7-client: + + :: + + > /disks> cd /iscsi-target/iqn.2003-01.com.redhat.iscsi-gw:iscsi-igw/hosts + > /iscsi-target...eph-igw/hosts> create iqn.1994-05.com.redhat:rh7-client + +#. Set the client's CHAP username to myiscsiusername and password to + myiscsipassword: + + :: + + > /iscsi-target...at:rh7-client> auth username=myiscsiusername password=myiscsipassword + + .. warning:: + CHAP must always be configured. Without CHAP, the target will + reject any login requests. + +#. Add the disk to the client: + + :: + + > /iscsi-target...at:rh7-client> disk add rbd/disk_1 + +The next step is to configure the iSCSI initiators. + +.. _`Ceph Command-line Interface`: ../../start/quick-rbd/#install-ceph + +.. toctree:: + :hidden: + + ../../start/quick-rbd diff --git a/doc/rbd/iscsi-targets.rst b/doc/rbd/iscsi-targets.rst new file mode 100644 index 000000000..d2a035283 --- /dev/null +++ b/doc/rbd/iscsi-targets.rst @@ -0,0 +1,27 @@ +============= +iSCSI Targets +============= + +Traditionally, block-level access to a Ceph storage cluster has been +limited to QEMU and ``librbd``, which is a key enabler for adoption +within OpenStack environments. Starting with the Ceph Luminous release, +block-level access is expanding to offer standard iSCSI support allowing +wider platform usage, and potentially opening new use cases. + +- Red Hat Enterprise Linux/CentOS 7.5 (or newer); Linux kernel v4.16 (or newer) + +- A working Ceph Storage cluster, deployed with ``ceph-ansible`` or using the command-line interface + +- iSCSI gateways nodes, which can either be colocated with OSD nodes or on dedicated nodes + +- Separate network subnets for iSCSI front-end traffic and Ceph back-end traffic + +A choice of using Ansible or the command-line interface are the +available deployment methods for installing and configuring the Ceph +iSCSI gateway: + +.. toctree:: + :maxdepth: 1 + + Using Ansible <iscsi-target-ansible> + Using the Command Line Interface <iscsi-target-cli> diff --git a/doc/rbd/libvirt.rst b/doc/rbd/libvirt.rst new file mode 100644 index 000000000..e3523f8a8 --- /dev/null +++ b/doc/rbd/libvirt.rst @@ -0,0 +1,323 @@ +================================= + Using libvirt with Ceph RBD +================================= + +.. index:: Ceph Block Device; livirt + +The ``libvirt`` library creates a virtual machine abstraction layer between +hypervisor interfaces and the software applications that use them. With +``libvirt``, developers and system administrators can focus on a common +management framework, common API, and common shell interface (i.e., ``virsh``) +to many different hypervisors, including: + +- QEMU/KVM +- XEN +- LXC +- VirtualBox +- etc. + +Ceph block devices support QEMU/KVM. You can use Ceph block devices with +software that interfaces with ``libvirt``. The following stack diagram +illustrates how ``libvirt`` and QEMU use Ceph block devices via ``librbd``. + + +.. ditaa:: + + +---------------------------------------------------+ + | libvirt | + +------------------------+--------------------------+ + | + | configures + v + +---------------------------------------------------+ + | QEMU | + +---------------------------------------------------+ + | librbd | + +---------------------------------------------------+ + | librados | + +------------------------+-+------------------------+ + | OSDs | | Monitors | + +------------------------+ +------------------------+ + + +The most common ``libvirt`` use case involves providing Ceph block devices to +cloud solutions like OpenStack or CloudStack. The cloud solution uses +``libvirt`` to interact with QEMU/KVM, and QEMU/KVM interacts with Ceph block +devices via ``librbd``. See `Block Devices and OpenStack`_ and `Block Devices +and CloudStack`_ for details. See `Installation`_ for installation details. + +You can also use Ceph block devices with ``libvirt``, ``virsh`` and the +``libvirt`` API. See `libvirt Virtualization API`_ for details. + + +To create VMs that use Ceph block devices, use the procedures in the following +sections. In the exemplary embodiment, we have used ``libvirt-pool`` for the pool +name, ``client.libvirt`` for the user name, and ``new-libvirt-image`` for the +image name. You may use any value you like, but ensure you replace those values +when executing commands in the subsequent procedures. + + +Configuring Ceph +================ + +To configure Ceph for use with ``libvirt``, perform the following steps: + +#. `Create a pool`_. The following example uses the + pool name ``libvirt-pool``.:: + + ceph osd pool create libvirt-pool + + Verify the pool exists. :: + + ceph osd lspools + +#. Use the ``rbd`` tool to initialize the pool for use by RBD:: + + rbd pool init <pool-name> + +#. `Create a Ceph User`_ (or use ``client.admin`` for version 0.9.7 and + earlier). The following example uses the Ceph user name ``client.libvirt`` + and references ``libvirt-pool``. :: + + ceph auth get-or-create client.libvirt mon 'profile rbd' osd 'profile rbd pool=libvirt-pool' + + Verify the name exists. :: + + ceph auth ls + + **NOTE**: ``libvirt`` will access Ceph using the ID ``libvirt``, + not the Ceph name ``client.libvirt``. See `User Management - User`_ and + `User Management - CLI`_ for a detailed explanation of the difference + between ID and name. + +#. Use QEMU to `create an image`_ in your RBD pool. + The following example uses the image name ``new-libvirt-image`` + and references ``libvirt-pool``. :: + + qemu-img create -f rbd rbd:libvirt-pool/new-libvirt-image 2G + + Verify the image exists. :: + + rbd -p libvirt-pool ls + + **NOTE:** You can also use `rbd create`_ to create an image, but we + recommend ensuring that QEMU is working properly. + +.. tip:: Optionally, if you wish to enable debug logs and the admin socket for + this client, you can add the following section to ``/etc/ceph/ceph.conf``:: + + [client.libvirt] + log file = /var/log/ceph/qemu-guest-$pid.log + admin socket = /var/run/ceph/$cluster-$type.$id.$pid.$cctid.asok + + The ``client.libvirt`` section name should match the cephx user you created + above. + If SELinux or AppArmor is enabled, note that this could prevent the client + process (qemu via libvirt) from doing some operations, such as writing logs + or operate the images or admin socket to the destination locations (``/var/ + log/ceph`` or ``/var/run/ceph``). Additionally, make sure that the libvirt + and qemu users have appropriate access to the specified directory. + + +Preparing the VM Manager +======================== + +You may use ``libvirt`` without a VM manager, but you may find it simpler to +create your first domain with ``virt-manager``. + +#. Install a virtual machine manager. See `KVM/VirtManager`_ for details. :: + + sudo apt-get install virt-manager + +#. Download an OS image (if necessary). + +#. Launch the virtual machine manager. :: + + sudo virt-manager + + + +Creating a VM +============= + +To create a VM with ``virt-manager``, perform the following steps: + +#. Press the **Create New Virtual Machine** button. + +#. Name the new virtual machine domain. In the exemplary embodiment, we + use the name ``libvirt-virtual-machine``. You may use any name you wish, + but ensure you replace ``libvirt-virtual-machine`` with the name you + choose in subsequent commandline and configuration examples. :: + + libvirt-virtual-machine + +#. Import the image. :: + + /path/to/image/recent-linux.img + + **NOTE:** Import a recent image. Some older images may not rescan for + virtual devices properly. + +#. Configure and start the VM. + +#. You may use ``virsh list`` to verify the VM domain exists. :: + + sudo virsh list + +#. Login to the VM (root/root) + +#. Stop the VM before configuring it for use with Ceph. + + +Configuring the VM +================== + +When configuring the VM for use with Ceph, it is important to use ``virsh`` +where appropriate. Additionally, ``virsh`` commands often require root +privileges (i.e., ``sudo``) and will not return appropriate results or notify +you that root privileges are required. For a reference of ``virsh`` +commands, refer to `Virsh Command Reference`_. + + +#. Open the configuration file with ``virsh edit``. :: + + sudo virsh edit {vm-domain-name} + + Under ``<devices>`` there should be a ``<disk>`` entry. :: + + <devices> + <emulator>/usr/bin/kvm</emulator> + <disk type='file' device='disk'> + <driver name='qemu' type='raw'/> + <source file='/path/to/image/recent-linux.img'/> + <target dev='vda' bus='virtio'/> + <address type='drive' controller='0' bus='0' unit='0'/> + </disk> + + + Replace ``/path/to/image/recent-linux.img`` with the path to the OS image. + The minimum kernel for using the faster ``virtio`` bus is 2.6.25. See + `Virtio`_ for details. + + **IMPORTANT:** Use ``sudo virsh edit`` instead of a text editor. If you edit + the configuration file under ``/etc/libvirt/qemu`` with a text editor, + ``libvirt`` may not recognize the change. If there is a discrepancy between + the contents of the XML file under ``/etc/libvirt/qemu`` and the result of + ``sudo virsh dumpxml {vm-domain-name}``, then your VM may not work + properly. + + +#. Add the Ceph RBD image you created as a ``<disk>`` entry. :: + + <disk type='network' device='disk'> + <source protocol='rbd' name='libvirt-pool/new-libvirt-image'> + <host name='{monitor-host}' port='6789'/> + </source> + <target dev='vdb' bus='virtio'/> + </disk> + + Replace ``{monitor-host}`` with the name of your host, and replace the + pool and/or image name as necessary. You may add multiple ``<host>`` + entries for your Ceph monitors. The ``dev`` attribute is the logical + device name that will appear under the ``/dev`` directory of your + VM. The optional ``bus`` attribute indicates the type of disk device to + emulate. The valid settings are driver specific (e.g., "ide", "scsi", + "virtio", "xen", "usb" or "sata"). + + See `Disks`_ for details of the ``<disk>`` element, and its child elements + and attributes. + +#. Save the file. + +#. If your Ceph Storage Cluster has `Ceph Authentication`_ enabled (it does by + default), you must generate a secret. :: + + cat > secret.xml <<EOF + <secret ephemeral='no' private='no'> + <usage type='ceph'> + <name>client.libvirt secret</name> + </usage> + </secret> + EOF + +#. Define the secret. :: + + sudo virsh secret-define --file secret.xml + {uuid of secret} + +#. Get the ``client.libvirt`` key and save the key string to a file. :: + + ceph auth get-key client.libvirt | sudo tee client.libvirt.key + +#. Set the UUID of the secret. :: + + sudo virsh secret-set-value --secret {uuid of secret} --base64 $(cat client.libvirt.key) && rm client.libvirt.key secret.xml + + You must also set the secret manually by adding the following ``<auth>`` + entry to the ``<disk>`` element you entered earlier (replacing the + ``uuid`` value with the result from the command line example above). :: + + sudo virsh edit {vm-domain-name} + + Then, add ``<auth></auth>`` element to the domain configuration file:: + + ... + </source> + <auth username='libvirt'> + <secret type='ceph' uuid='{uuid of secret}'/> + </auth> + <target ... + + + **NOTE:** The exemplary ID is ``libvirt``, not the Ceph name + ``client.libvirt`` as generated at step 2 of `Configuring Ceph`_. Ensure + you use the ID component of the Ceph name you generated. If for some reason + you need to regenerate the secret, you will have to execute + ``sudo virsh secret-undefine {uuid}`` before executing + ``sudo virsh secret-set-value`` again. + + +Summary +======= + +Once you have configured the VM for use with Ceph, you can start the VM. +To verify that the VM and Ceph are communicating, you may perform the +following procedures. + + +#. Check to see if Ceph is running:: + + ceph health + +#. Check to see if the VM is running. :: + + sudo virsh list + +#. Check to see if the VM is communicating with Ceph. Replace + ``{vm-domain-name}`` with the name of your VM domain:: + + sudo virsh qemu-monitor-command --hmp {vm-domain-name} 'info block' + +#. Check to see if the device from ``<target dev='vdb' bus='virtio'/>`` exists:: + + virsh domblklist {vm-domain-name} --details + +If everything looks okay, you may begin using the Ceph block device +within your VM. + + +.. _Installation: ../../install +.. _libvirt Virtualization API: http://www.libvirt.org +.. _Block Devices and OpenStack: ../rbd-openstack +.. _Block Devices and CloudStack: ../rbd-cloudstack +.. _Create a pool: ../../rados/operations/pools#create-a-pool +.. _Create a Ceph User: ../../rados/operations/user-management#add-a-user +.. _create an image: ../qemu-rbd#creating-images-with-qemu +.. _Virsh Command Reference: http://www.libvirt.org/virshcmdref.html +.. _KVM/VirtManager: https://help.ubuntu.com/community/KVM/VirtManager +.. _Ceph Authentication: ../../rados/configuration/auth-config-ref +.. _Disks: http://www.libvirt.org/formatdomain.html#elementsDisks +.. _rbd create: ../rados-rbd-cmds#creating-a-block-device-image +.. _User Management - User: ../../rados/operations/user-management#user +.. _User Management - CLI: ../../rados/operations/user-management#command-line-usage +.. _Virtio: http://www.linux-kvm.org/page/Virtio diff --git a/doc/rbd/man/index.rst b/doc/rbd/man/index.rst new file mode 100644 index 000000000..110273acc --- /dev/null +++ b/doc/rbd/man/index.rst @@ -0,0 +1,16 @@ +============================ + Ceph Block Device Manpages +============================ + +.. toctree:: + :maxdepth: 1 + + rbd <../../man/8/rbd> + rbd-fuse <../../man/8/rbd-fuse> + rbd-nbd <../../man/8/rbd-nbd> + rbd-ggate <../../man/8/rbd-ggate> + rbd-map <../../man/8/rbdmap> + ceph-rbdnamer <../../man/8/ceph-rbdnamer> + rbd-replay-prep <../../man/8/rbd-replay-prep> + rbd-replay <../../man/8/rbd-replay> + rbd-replay-many <../../man/8/rbd-replay-many> diff --git a/doc/rbd/qemu-rbd.rst b/doc/rbd/qemu-rbd.rst new file mode 100644 index 000000000..f5925d6c3 --- /dev/null +++ b/doc/rbd/qemu-rbd.rst @@ -0,0 +1,220 @@ +======================== + QEMU and Block Devices +======================== + +.. index:: Ceph Block Device; QEMU KVM + +The most frequent Ceph Block Device use case involves providing block device +images to virtual machines. For example, a user may create a "golden" image +with an OS and any relevant software in an ideal configuration. Then the user +takes a snapshot of the image. Finally the user clones the snapshot (potentially +many times). See `Snapshots`_ for details. The ability to make copy-on-write +clones of a snapshot means that Ceph can provision block device images to +virtual machines quickly, because the client doesn't have to download the entire +image each time it spins up a new virtual machine. + + +.. ditaa:: + + +---------------------------------------------------+ + | QEMU | + +---------------------------------------------------+ + | librbd | + +---------------------------------------------------+ + | librados | + +------------------------+-+------------------------+ + | OSDs | | Monitors | + +------------------------+ +------------------------+ + + +Ceph Block Devices attach to QEMU virtual machines. For details on +QEMU, see `QEMU Open Source Processor Emulator`_. For QEMU documentation, see +`QEMU Manual`_. For installation details, see `Installation`_. + +.. important:: To use Ceph Block Devices with QEMU, you must have access to a + running Ceph cluster. + + +Usage +===== + +The QEMU command line expects you to specify the Ceph pool and image name. You +may also specify a snapshot. + +QEMU will assume that Ceph configuration resides in the default +location (e.g., ``/etc/ceph/$cluster.conf``) and that you are executing +commands as the default ``client.admin`` user unless you expressly specify +another Ceph configuration file path or another user. When specifying a user, +QEMU uses the ``ID`` rather than the full ``TYPE:ID``. See `User Management - +User`_ for details. Do not prepend the client type (i.e., ``client.``) to the +beginning of the user ``ID``, or you will receive an authentication error. You +should have the key for the ``admin`` user or the key of another user you +specify with the ``:id={user}`` option in a keyring file stored in default path +(i.e., ``/etc/ceph`` or the local directory with appropriate file ownership and +permissions. Usage takes the following form:: + + qemu-img {command} [options] rbd:{pool-name}/{image-name}[@snapshot-name][:option1=value1][:option2=value2...] + +For example, specifying the ``id`` and ``conf`` options might look like the following:: + + qemu-img {command} [options] rbd:glance-pool/maipo:id=glance:conf=/etc/ceph/ceph.conf + +.. tip:: Configuration values containing ``:``, ``@``, or ``=`` can be escaped with a + leading ``\`` character. + + +Creating Images with QEMU +========================= + +You can create a block device image from QEMU. You must specify ``rbd``, the +pool name, and the name of the image you wish to create. You must also specify +the size of the image. :: + + qemu-img create -f raw rbd:{pool-name}/{image-name} {size} + +For example:: + + qemu-img create -f raw rbd:data/foo 10G + +.. important:: The ``raw`` data format is really the only sensible + ``format`` option to use with RBD. Technically, you could use other + QEMU-supported formats (such as ``qcow2`` or ``vmdk``), but doing + so would add additional overhead, and would also render the volume + unsafe for virtual machine live migration when caching (see below) + is enabled. + + +Resizing Images with QEMU +========================= + +You can resize a block device image from QEMU. You must specify ``rbd``, +the pool name, and the name of the image you wish to resize. You must also +specify the size of the image. :: + + qemu-img resize rbd:{pool-name}/{image-name} {size} + +For example:: + + qemu-img resize rbd:data/foo 10G + + +Retrieving Image Info with QEMU +=============================== + +You can retrieve block device image information from QEMU. You must +specify ``rbd``, the pool name, and the name of the image. :: + + qemu-img info rbd:{pool-name}/{image-name} + +For example:: + + qemu-img info rbd:data/foo + + +Running QEMU with RBD +===================== + +QEMU can pass a block device from the host on to a guest, but since +QEMU 0.15, there's no need to map an image as a block device on +the host. Instead, QEMU attaches an image as a virtual block +device directly via ``librbd``. This strategy increases performance +by avoiding context switches and taking advantage of `RBD caching`_. + +You can use ``qemu-img`` to convert existing virtual machine images to Ceph +block device images. For example, if you have a qcow2 image, you could run:: + + qemu-img convert -f qcow2 -O raw debian_squeeze.qcow2 rbd:data/squeeze + +To run a virtual machine booting from that image, you could run:: + + qemu -m 1024 -drive format=raw,file=rbd:data/squeeze + +`RBD caching`_ can significantly improve performance. +Since QEMU 1.2, QEMU's cache options control ``librbd`` caching:: + + qemu -m 1024 -drive format=rbd,file=rbd:data/squeeze,cache=writeback + +If you have an older version of QEMU, you can set the ``librbd`` cache +configuration (like any Ceph configuration option) as part of the +'file' parameter:: + + qemu -m 1024 -drive format=raw,file=rbd:data/squeeze:rbd_cache=true,cache=writeback + +.. important:: If you set rbd_cache=true, you must set cache=writeback + or risk data loss. Without cache=writeback, QEMU will not send + flush requests to librbd. If QEMU exits uncleanly in this + configuration, file systems on top of rbd can be corrupted. + +.. _RBD caching: ../rbd-config-ref/#rbd-cache-config-settings + + +.. index:: Ceph Block Device; discard trim and libvirt + +Enabling Discard/TRIM +===================== + +Since Ceph version 0.46 and QEMU version 1.1, Ceph Block Devices support the +discard operation. This means that a guest can send TRIM requests to let a Ceph +block device reclaim unused space. This can be enabled in the guest by mounting +``ext4`` or ``XFS`` with the ``discard`` option. + +For this to be available to the guest, it must be explicitly enabled +for the block device. To do this, you must specify a +``discard_granularity`` associated with the drive:: + + qemu -m 1024 -drive format=raw,file=rbd:data/squeeze,id=drive1,if=none \ + -device driver=ide-hd,drive=drive1,discard_granularity=512 + +Note that this uses the IDE driver. The virtio driver does not +support discard. + +If using libvirt, edit your libvirt domain's configuration file using ``virsh +edit`` to include the ``xmlns:qemu`` value. Then, add a ``qemu:commandline`` +block as a child of that domain. The following example shows how to set two +devices with ``qemu id=`` to different ``discard_granularity`` values. + +.. code-block:: xml + + <domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'> + <qemu:commandline> + <qemu:arg value='-set'/> + <qemu:arg value='block.scsi0-0-0.discard_granularity=4096'/> + <qemu:arg value='-set'/> + <qemu:arg value='block.scsi0-0-1.discard_granularity=65536'/> + </qemu:commandline> + </domain> + + +.. index:: Ceph Block Device; cache options + +QEMU Cache Options +================== + +QEMU's cache options correspond to the following Ceph `RBD Cache`_ settings. + +Writeback:: + + rbd_cache = true + +Writethrough:: + + rbd_cache = true + rbd_cache_max_dirty = 0 + +None:: + + rbd_cache = false + +QEMU's cache settings override Ceph's cache settings (including settings that +are explicitly set in the Ceph configuration file). + +.. note:: Prior to QEMU v2.4.0, if you explicitly set `RBD Cache`_ settings + in the Ceph configuration file, your Ceph settings override the QEMU cache + settings. + +.. _QEMU Open Source Processor Emulator: http://wiki.qemu.org/Main_Page +.. _QEMU Manual: http://wiki.qemu.org/Manual +.. _RBD Cache: ../rbd-config-ref/ +.. _Snapshots: ../rbd-snapshot/ +.. _Installation: ../../install +.. _User Management - User: ../../rados/operations/user-management#user diff --git a/doc/rbd/rados-rbd-cmds.rst b/doc/rbd/rados-rbd-cmds.rst new file mode 100644 index 000000000..0bbcb2611 --- /dev/null +++ b/doc/rbd/rados-rbd-cmds.rst @@ -0,0 +1,326 @@ +============================= + Basic Block Device Commands +============================= + +.. index:: Ceph Block Device; image management + +The ``rbd`` command enables you to create, list, introspect and remove block +device images. You can also use it to clone images, create snapshots, +rollback an image to a snapshot, view a snapshot, etc. For details on using +the ``rbd`` command, see `RBD – Manage RADOS Block Device (RBD) Images`_ for +details. + +.. important:: To use Ceph Block Device commands, you must have access to + a running Ceph cluster. + +Create a Block Device Pool +========================== + +#. Use the ``ceph`` tool to `create a pool`_. + +#. Use the ``rbd`` tool to initialize the pool for use by RBD: + + .. prompt:: bash $ + + rbd pool init <pool-name> + + .. note:: The ``rbd`` tool assumes a default pool name of 'rbd' if no pool + name is specified in the command. + + +Create a Block Device User +========================== + +Unless otherwise specified, the ``rbd`` command uses the Ceph user ID ``admin`` +to access the Ceph cluster. The ``admin`` Ceph user ID allows full +administrative access to the cluster. We recommend that you acess the Ceph +cluster with a Ceph user ID that has fewer permissions than the ``admin`` Ceph +user ID does. We call this non-``admin`` Ceph user ID a "block device user" or +"Ceph user". + +To `create a Ceph user`_, use the ``ceph auth get-or-create`` command to +specify the Ceph user ID name, monitor caps (capabilities), and OSD caps +(capabilities): + +.. prompt:: bash $ + + ceph auth get-or-create client.{ID} mon 'profile rbd' osd 'profile {profile name} [pool={pool-name}][, profile ...]' mgr 'profile rbd [pool={pool-name}]' + +For example: to create a Ceph user ID named ``qemu`` that has read-write access +to the pool ``vms`` and read-only access to the pool ``images``, run the +following command: + +.. prompt:: bash $ + + ceph auth get-or-create client.qemu mon 'profile rbd' osd 'profile rbd pool=vms, profile rbd-read-only pool=images' mgr 'profile rbd pool=images' + +The output from the ``ceph auth get-or-create`` command is the keyring for the +specified Ceph user ID, which can be written to +``/etc/ceph/ceph.client.{ID}.keyring``. + +.. note:: Specify the Ceph user ID by providing the ``--id {id} argument when + using the ``rbd`` command. This argument is optional. + +Creating a Block Device Image +============================= + +Before you can add a block device to a node, you must create an image for it in +the :term:`Ceph Storage Cluster`. To create a block device image, run a command of this form: + +.. prompt:: bash $ + + rbd create --size {megabytes} {pool-name}/{image-name} + +For example, to create a 1GB image named ``bar`` that stores information in a +pool named ``swimmingpool``, run this command: + +.. prompt:: bash $ + + rbd create --size 1024 swimmingpool/bar + +If you don't specify a pool when you create an image, then the image will be +stored in the default pool ``rbd``. For example, if you ran this command, you +would create a 1GB image named ``foo`` that is stored in the default pool +``rbd``: + +.. prompt:: bash $ + + rbd create --size 1024 foo + +.. note:: You must create a pool before you can specify it as a source. See + `Storage Pools`_ for details. + +Listing Block Device Images +=========================== + +To list block devices in the ``rbd`` pool, run the following command: + +.. prompt:: bash $ + + rbd ls + +.. note:: ``rbd`` is the default pool name, and ``rbd ls`` lists the commands + in the default pool. + +To list block devices in a particular pool, run the following command, but +replace ``{poolname}`` with the name of the pool: + +.. prompt:: bash $ + + rbd ls {poolname} + +For example: + +.. prompt:: bash $ + + rbd ls swimmingpool + +To list "deferred delete" block devices in the ``rbd`` pool, run the +following command: + +.. prompt:: bash $ + + rbd trash ls + +To list "deferred delete" block devices in a particular pool, run the +following command, but replace ``{poolname}`` with the name of the pool: + +.. prompt:: bash $ + + rbd trash ls {poolname} + +For example: + +.. prompt:: bash $ + + rbd trash ls swimmingpool + +Retrieving Image Information +============================ + +To retrieve information from a particular image, run the following command, but +replace ``{image-name}`` with the name for the image: + +.. prompt:: bash $ + + rbd info {image-name} + +For example: + +.. prompt:: bash $ + + rbd info foo + +To retrieve information from an image within a pool, run the following command, +but replace ``{image-name}`` with the name of the image and replace +``{pool-name}`` with the name of the pool: + +.. prompt:: bash $ + + rbd info {pool-name}/{image-name} + +For example: + +.. prompt:: bash $ + + rbd info swimmingpool/bar + +.. note:: Other naming conventions are possible, and might conflict with the + naming convention described here. For example, ``userid/<uuid>`` is a + possible name for an RBD image, and such a name might (at the least) be + confusing. + +Resizing a Block Device Image +============================= + +:term:`Ceph Block Device` images are thin provisioned. They don't actually use +any physical storage until you begin saving data to them. However, they do have +a maximum capacity that you set with the ``--size`` option. If you want to +increase (or decrease) the maximum size of a Ceph Block Device image, run one +of the following commands: + +Increasing the Size of a Block Device Image +------------------------------------------- + +.. prompt:: bash $ + + rbd resize --size 2048 foo + +Decreasing the Size of a Block Device Image +------------------------------------------- + +.. prompt:: bash $ + + rbd resize --size 2048 foo --allow-shrink + + +Removing a Block Device Image +============================= + +To remove a block device, run the following command, but replace +``{image-name}`` with the name of the image you want to remove: + +.. prompt:: bash $ + + rbd rm {image-name} + +For example: + +.. prompt:: bash $ + + rbd rm foo + +Removing a Block Device from a Pool +----------------------------------- + +To remove a block device from a pool, run the following command but replace +``{image-name}`` with the name of the image to be removed, and replace +``{pool-name}`` with the name of the pool from which the image is to be +removed: + +.. prompt:: bash $ + + rbd rm {pool-name}/{image-name} + +For example: + +.. prompt:: bash $ + + rbd rm swimmingpool/bar + +"Defer Deleting" a Block Device from a Pool +------------------------------------------- + +To defer delete a block device from a pool (which entails moving it to the +"trash" and deleting it later), run the following command but replace +``{image-name}`` with the name of the image to be moved to the trash and +replace ``{pool-name}`` with the name of the pool: + +.. prompt:: bash $ + + rbd trash mv {pool-name}/{image-name} + +For example: + +.. prompt:: bash $ + + rbd trash mv swimmingpool/bar + +Removing a Deferred Block Device from a Pool +-------------------------------------------- + +To remove a deferred block device from a pool, run the following command but +replace ``{image-}`` with the ID of the image to be removed, and replace +``{pool-name}`` with the name of the pool from which the image is to be +removed: + +.. prompt:: bash $ + + rbd trash rm {pool-name}/{image-} + +For example: + +.. prompt:: bash $ + + rbd trash rm swimmingpool/2bf4474b0dc51 + +.. note:: + + * You can move an image to the trash even if it has snapshot(s) or is + actively in use by clones. However, you cannot remove it from the trash + under those conditions. + + * You can use ``--expires-at`` to set the deferment time (default is + ``now``). If the deferment time has not yet arrived, you cannot remove the + image unless you use ``--force``. + +Restoring a Block Device Image +============================== + +To restore a deferred delete block device in the rbd pool, run the +following command but replace ``{image-id}`` with the ID of the image: + +.. prompt:: bash $ + + rbd trash restore {image-id} + +For example: + +.. prompt:: bash $ + + rbd trash restore 2bf4474b0dc51 + +Restoring a Block Device Image in a Specific Pool +------------------------------------------------- + +To restore a deferred delete block device in a particular pool, run the +following command but replace ``{image-id}`` with the ID of the image and +replace ``{pool-name}`` with the name of the pool: + +.. prompt:: bash $ + + rbd trash restore {pool-name}/{image-id} + +For example: + +.. prompt:: bash $ + + rbd trash restore swimmingpool/2bf4474b0dc51 + + +Renaming an Image While Restoring It +------------------------------------ + +You can also use ``--image`` to rename the image while restoring it. + +For example: + +.. prompt:: bash $ + + rbd trash restore swimmingpool/2bf4474b0dc51 --image new-name + + +.. _create a pool: ../../rados/operations/pools/#create-a-pool +.. _Storage Pools: ../../rados/operations/pools +.. _RBD – Manage RADOS Block Device (RBD) Images: ../../man/8/rbd/ +.. _create a Ceph user: ../../rados/operations/user-management#add-a-user diff --git a/doc/rbd/rbd-cloudstack.rst b/doc/rbd/rbd-cloudstack.rst new file mode 100644 index 000000000..1b961234b --- /dev/null +++ b/doc/rbd/rbd-cloudstack.rst @@ -0,0 +1,157 @@ +============================= + Block Devices and CloudStack +============================= + +You may use Ceph Block Device images with CloudStack 4.0 and higher through +``libvirt``, which configures the QEMU interface to ``librbd``. Ceph stripes +block device images as objects across the cluster, which means that large Ceph +Block Device images have better performance than a standalone server! + +To use Ceph Block Devices with CloudStack 4.0 and higher, you must install QEMU, +``libvirt``, and CloudStack first. We recommend using a separate physical host +for your CloudStack installation. CloudStack recommends a minimum of 4GB of RAM +and a dual-core processor, but more CPU and RAM will perform better. The +following diagram depicts the CloudStack/Ceph technology stack. + + +.. ditaa:: + + +---------------------------------------------------+ + | CloudStack | + +---------------------------------------------------+ + | libvirt | + +------------------------+--------------------------+ + | + | configures + v + +---------------------------------------------------+ + | QEMU | + +---------------------------------------------------+ + | librbd | + +---------------------------------------------------+ + | librados | + +------------------------+-+------------------------+ + | OSDs | | Monitors | + +------------------------+ +------------------------+ + +.. important:: To use Ceph Block Devices with CloudStack, you must have + access to a running Ceph Storage Cluster. + +CloudStack integrates with Ceph's block devices to provide CloudStack with a +back end for CloudStack's Primary Storage. The instructions below detail the +setup for CloudStack Primary Storage. + +.. note:: We recommend installing with Ubuntu 14.04 or later so that + you can use package installation instead of having to compile + libvirt from source. + +Installing and configuring QEMU for use with CloudStack doesn't require any +special handling. Ensure that you have a running Ceph Storage Cluster. Install +QEMU and configure it for use with Ceph; then, install ``libvirt`` version +0.9.13 or higher (you may need to compile from source) and ensure it is running +with Ceph. + + +.. note:: Ubuntu 14.04 and CentOS 7.2 will have ``libvirt`` with RBD storage + pool support enabled by default. + +.. index:: pools; CloudStack + +Create a Pool +============= + +By default, Ceph block devices use the ``rbd`` pool. Create a pool for +CloudStack NFS Primary Storage. Ensure your Ceph cluster is running, then create +the pool. :: + + ceph osd pool create cloudstack + +See `Create a Pool`_ for details on specifying the number of placement groups +for your pools, and `Placement Groups`_ for details on the number of placement +groups you should set for your pools. + +A newly created pool must be initialized prior to use. Use the ``rbd`` tool +to initialize the pool:: + + rbd pool init cloudstack + +Create a Ceph User +================== + +To access the Ceph cluster we require a Ceph user which has the correct +credentials to access the ``cloudstack`` pool we just created. Although we could +use ``client.admin`` for this, it's recommended to create a user with only +access to the ``cloudstack`` pool. :: + + ceph auth get-or-create client.cloudstack mon 'profile rbd' osd 'profile rbd pool=cloudstack' + +Use the information returned by the command in the next step when adding the +Primary Storage. + +See `User Management`_ for additional details. + +Add Primary Storage +=================== + +To add a Ceph block device as Primary Storage, the steps include: + +#. Log in to the CloudStack UI. +#. Click **Infrastructure** on the left side navigation bar. +#. Select **View All** under **Primary Storage**. +#. Click the **Add Primary Storage** button on the top right hand side. +#. Fill in the following information, according to your infrastructure setup: + + - Scope (i.e. Cluster or Zone-Wide). + + - Zone. + + - Pod. + + - Cluster. + + - Name of Primary Storage. + + - For **Protocol**, select ``RBD``. + + - For **Provider**, select the appropriate provider type (i.e. DefaultPrimary, SolidFire, SolidFireShared, or CloudByte). Depending on the provider chosen, fill out the information pertinent to your setup. + +#. Add cluster information (``cephx`` is supported). + + - For **RADOS Monitor**, provide the IP address of a Ceph monitor node. + + - For **RADOS Pool**, provide the name of an RBD pool. + + - For **RADOS User**, provide a user that has sufficient rights to the RBD pool. Note: Do not include the ``client.`` part of the user. + + - For **RADOS Secret**, provide the secret the user's secret. + + - **Storage Tags** are optional. Use tags at your own discretion. For more information about storage tags in CloudStack, refer to `Storage Tags`_. + +#. Click **OK**. + +Create a Disk Offering +====================== + +To create a new disk offering, refer to `Create a New Disk Offering`_. +Create a disk offering so that it matches the ``rbd`` tag. +The ``StoragePoolAllocator`` will choose the ``rbd`` +pool when searching for a suitable storage pool. If the disk offering doesn't +match the ``rbd`` tag, the ``StoragePoolAllocator`` may select the pool you +created (e.g., ``cloudstack``). + + +Limitations +=========== + +- CloudStack will only bind to one monitor (You can however create a Round Robin DNS record over multiple monitors) + + + +.. _Create a Pool: ../../rados/operations/pools#createpool +.. _Placement Groups: ../../rados/operations/placement-groups +.. _Install and Configure QEMU: ../qemu-rbd +.. _Install and Configure libvirt: ../libvirt +.. _KVM Hypervisor Host Installation: http://docs.cloudstack.apache.org/en/latest/installguide/hypervisor/kvm.html +.. _Storage Tags: http://docs.cloudstack.apache.org/en/latest/adminguide/storage.html#storage-tags +.. _Create a New Disk Offering: http://docs.cloudstack.apache.org/en/latest/adminguide/service_offerings.html#creating-a-new-disk-offering +.. _User Management: ../../rados/operations/user-management diff --git a/doc/rbd/rbd-config-ref.rst b/doc/rbd/rbd-config-ref.rst new file mode 100644 index 000000000..777894cd6 --- /dev/null +++ b/doc/rbd/rbd-config-ref.rst @@ -0,0 +1,476 @@ +======================= + Config Settings +======================= + +See `Block Device`_ for additional details. + +Generic IO Settings +=================== + +``rbd_compression_hint`` + +:Description: Hint to send to the OSDs on write operations. If set to + ``compressible`` and the OSD ``bluestore_compression_mode`` + setting is ``passive``, the OSD will attempt to compress data + If set to ``incompressible`` and the OSD compression setting + is ``aggressive``, the OSD will not attempt to compress data. +:Type: Enum +:Required: No +:Default: ``none`` +:Values: ``none``, ``compressible``, ``incompressible`` + + +``rbd_read_from_replica_policy`` + +:Description: Policy for determining which OSD will receive read operations. + If set to ``default``, each PG's primary OSD will always be used + for read operations. If set to ``balance``, read operations will + be sent to a randomly selected OSD within the replica set. If set + to ``localize``, read operations will be sent to the closest OSD + as determined by the CRUSH map. Note: this feature requires the + cluster to be configured with a minimum compatible OSD release of + Octopus. +:Type: Enum +:Required: No +:Default: ``default`` +:Values: ``default``, ``balance``, ``localize`` + +Cache Settings +======================= + +.. sidebar:: Kernel Caching + + The kernel driver for Ceph block devices can use the Linux page cache to + improve performance. + +The user space implementation of the Ceph block device (i.e., ``librbd``) cannot +take advantage of the Linux page cache, so it includes its own in-memory +caching, called "RBD caching." RBD caching behaves just like well-behaved hard +disk caching. When the OS sends a barrier or a flush request, all dirty data is +written to the OSDs. This means that using write-back caching is just as safe as +using a well-behaved physical hard disk with a VM that properly sends flushes +(i.e. Linux kernel >= 2.6.32). The cache uses a Least Recently Used (LRU) +algorithm, and in write-back mode it can coalesce contiguous requests for +better throughput. + +The librbd cache is enabled by default and supports three different cache +policies: write-around, write-back, and write-through. Writes return +immediately under both the write-around and write-back policies, unless there +are more than ``rbd_cache_max_dirty`` unwritten bytes to the storage cluster. +The write-around policy differs from the write-back policy in that it does +not attempt to service read requests from the cache, unlike the write-back +policy, and is therefore faster for high performance write workloads. Under the +write-through policy, writes return only when the data is on disk on all +replicas, but reads may come from the cache. + +Prior to receiving a flush request, the cache behaves like a write-through cache +to ensure safe operation for older operating systems that do not send flushes to +ensure crash consistent behavior. + +If the librbd cache is disabled, writes and +reads go directly to the storage cluster, and writes return only when the data +is on disk on all replicas. + +.. note:: + The cache is in memory on the client, and each RBD image has + its own. Since the cache is local to the client, there's no coherency + if there are others accessing the image. Running GFS or OCFS on top of + RBD will not work with caching enabled. + + +Option settings for RBD should be set in the ``[client]`` +section of your configuration file or the central config store. These settings +include: + +``rbd_cache`` + +:Description: Enable caching for RADOS Block Device (RBD). +:Type: Boolean +:Required: No +:Default: ``true`` + + +``rbd_cache_policy`` + +:Description: Select the caching policy for librbd. +:Type: Enum +:Required: No +:Default: ``writearound`` +:Values: ``writearound``, ``writeback``, ``writethrough`` + + +``rbd_cache_writethrough_until_flush`` + +:Description: Start out in ``writethrough`` mode, and switch to ``writeback`` + after the first flush request is received. Enabling is a + conservative but safe strategy in case VMs running on RBD volumes + are too old to send flushes, like the ``virtio`` driver in Linux + kernels older than 2.6.32. +:Type: Boolean +:Required: No +:Default: ``true`` + + +``rbd_cache_size`` + +:Description: The per-volume RBD client cache size in bytes. +:Type: 64-bit Integer +:Required: No +:Default: ``32 MiB`` +:Policies: write-back and write-through + + +``rbd_cache_max_dirty`` + +:Description: The ``dirty`` limit in bytes at which the cache triggers write-back. If ``0``, uses write-through caching. +:Type: 64-bit Integer +:Required: No +:Constraint: Must be less than ``rbd_cache_size``. +:Default: ``24 MiB`` +:Policies: write-around and write-back + + +``rbd_cache_target_dirty`` + +:Description: The ``dirty target`` before the cache begins writing data to the data storage. Does not block writes to the cache. +:Type: 64-bit Integer +:Required: No +:Constraint: Must be less than ``rbd_cache_max_dirty``. +:Default: ``16 MiB`` +:Policies: write-back + + +``rbd_cache_max_dirty_age`` + +:Description: The number of seconds dirty data is in the cache before writeback starts. +:Type: Float +:Required: No +:Default: ``1.0`` +:Policies: write-back + + +.. _Block Device: ../../rbd + + +Read-ahead Settings +======================= + +librbd supports read-ahead/prefetching to optimize small, sequential reads. +This should normally be handled by the guest OS in the case of a VM, +but boot loaders may not issue efficient reads. Read-ahead is automatically +disabled if caching is disabled or if the policy is write-around. + + +``rbd_readahead_trigger_requests`` + +:Description: Number of sequential read requests necessary to trigger read-ahead. +:Type: Integer +:Required: No +:Default: ``10`` + + +``rbd_readahead_max_bytes`` + +:Description: Maximum size of a read-ahead request. If zero, read-ahead is disabled. +:Type: 64-bit Integer +:Required: No +:Default: ``512 KiB`` + + +``rbd_readahead_disable_after_bytes`` + +:Description: After this many bytes have been read from an RBD image, read-ahead + is disabled for that image until it is closed. This allows the + guest OS to take over read-ahead once it is booted. If zero, + read-ahead stays enabled. +:Type: 64-bit Integer +:Required: No +:Default: ``50 MiB`` + + +Image Features +============== + +RBD supports advanced features which can be specified via the command line when +creating images or the default features can be configured via +``rbd_default_features = <sum of feature numeric values>`` or +``rbd_default_features = <comma-delimited list of CLI values>``. + +``Layering`` + +:Description: Layering enables cloning. +:Internal value: 1 +:CLI value: layering +:Added in: v0.52 (Bobtail) +:KRBD support: since v3.10 +:Default: yes + +``Striping v2`` + +:Description: Striping spreads data across multiple objects. Striping helps with + parallelism for sequential read/write workloads. +:Internal value: 2 +:CLI value: striping +:Added in: v0.55 (Bobtail) +:KRBD support: since v3.10 (default striping only, "fancy" striping added in v4.17) +:Default: yes + +``Exclusive locking`` + +:Description: When enabled, it requires a client to acquire a lock on an object + before making a write. Exclusive lock should only be enabled when + a single client is accessing an image at any given time. +:Internal value: 4 +:CLI value: exclusive-lock +:Added in: v0.92 (Hammer) +:KRBD support: since v4.9 +:Default: yes + +``Object map`` + +:Description: Object map support depends on exclusive lock support. Block + devices are thin provisioned, which means that they only store + data that actually has been written, ie. they are *sparse*. Object + map support helps track which objects actually exist (have data + stored on a device). Enabling object map support speeds up I/O + operations for cloning, importing and exporting a sparsely + populated image, and deleting. +:Internal value: 8 +:CLI value: object-map +:Added in: v0.93 (Hammer) +:KRBD support: since v5.3 +:Default: yes + + +``Fast-diff`` + +:Description: Fast-diff support depends on object map support and exclusive lock + support. It adds another property to the object map, which makes + it much faster to generate diffs between snapshots of an image. + It is also much faster to calculate the actual data usage of a + snapshot or volume (``rbd du``). +:Internal value: 16 +:CLI value: fast-diff +:Added in: v9.0.1 (Infernalis) +:KRBD support: since v5.3 +:Default: yes + + +``Deep-flatten`` + +:Description: Deep-flatten enables ``rbd flatten`` to work on all snapshots of + an image, in addition to the image itself. Without it, snapshots + of an image will still rely on the parent, so the parent cannot be + deleted until the snapshots are first deleted. Deep-flatten makes + a parent independent of its clones, even if they have snapshots, + at the expense of using additional OSD device space. +:Internal value: 32 +:CLI value: deep-flatten +:Added in: v9.0.2 (Infernalis) +:KRBD support: since v5.1 +:Default: yes + + +``Journaling`` + +:Description: Journaling support depends on exclusive lock support. Journaling + records all modifications to an image in the order they occur. RBD + mirroring can utilize the journal to replicate a crash-consistent + image to a remote cluster. It is best to let ``rbd-mirror`` + manage this feature only as needed, as enabling it long term may + result in substantial additional OSD space consumption. +:Internal value: 64 +:CLI value: journaling +:Added in: v10.0.1 (Jewel) +:KRBD support: no +:Default: no + + +``Data pool`` + +:Description: On erasure-coded pools, the image data block objects need to be stored on a separate pool from the image metadata. +:Internal value: 128 +:Added in: v11.1.0 (Kraken) +:KRBD support: since v4.11 +:Default: no + + +``Operations`` + +:Description: Used to restrict older clients from performing certain maintenance operations against an image (e.g. clone, snap create). +:Internal value: 256 +:Added in: v13.0.2 (Mimic) +:KRBD support: since v4.16 + + +``Migrating`` + +:Description: Used to restrict older clients from opening an image when it is in migration state. +:Internal value: 512 +:Added in: v14.0.1 (Nautilus) +:KRBD support: no + +``Non-primary`` + +:Description: Used to restrict changes to non-primary images using snapshot-based mirroring. +:Internal value: 1024 +:Added in: v15.2.0 (Octopus) +:KRBD support: no + + +QOS Settings +============ + +librbd supports limiting per-image IO, controlled by the following +settings. + +``rbd_qos_iops_limit`` + +:Description: The desired limit of IO operations per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_bps_limit`` + +:Description: The desired limit of IO bytes per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_read_iops_limit`` + +:Description: The desired limit of read operations per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_write_iops_limit`` + +:Description: The desired limit of write operations per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_read_bps_limit`` + +:Description: The desired limit of read bytes per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_writ_bps_limit`` + +:Description: The desired limit of write bytes per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_iops_burst`` + +:Description: The desired burst limit of IO operations. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_bps_burst`` + +:Description: The desired burst limit of IO bytes. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_read_iops_burst`` + +:Description: The desired burst limit of read operations. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_write_iops_burst`` + +:Description: The desired burst limit of write operations. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_read_bps_burst`` + +:Description: The desired burst limit of read bytes per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_write_bps_burst`` + +:Description: The desired burst limit of write bytes per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``rbd_qos_iops_burst_seconds`` + +:Description: The desired burst duration in seconds of IO operations. +:Type: Unsigned Integer +:Required: No +:Default: ``1`` + + +``rbd_qos_bps_burst_seconds`` + +:Description: The desired burst duration in seconds. +:Type: Unsigned Integer +:Required: No +:Default: ``1`` + + +``rbd_qos_read_iops_burst_seconds`` + +:Description: The desired burst duration in seconds of read operations. +:Type: Unsigned Integer +:Required: No +:Default: ``1`` + + +``rbd_qos_write_iops_burst_seconds`` + +:Description: The desired burst duration in seconds of write operations. +:Type: Unsigned Integer +:Required: No +:Default: ``1`` + + +``rbd_qos_read_bps_burst_seconds`` + +:Description: The desired burst duration in seconds of read bytes. +:Type: Unsigned Integer +:Required: No +:Default: ``1`` + + +``rbd_qos_write_bps_burst_seconds`` + +:Description: The desired burst duration in seconds of write bytes. +:Type: Unsigned Integer +:Required: No +:Default: ``1`` + + +``rbd_qos_schedule_tick_min`` + +:Description: The minimum schedule tick (in milliseconds) for QoS. +:Type: Unsigned Integer +:Required: No +:Default: ``50`` diff --git a/doc/rbd/rbd-encryption.rst b/doc/rbd/rbd-encryption.rst new file mode 100644 index 000000000..0628f3781 --- /dev/null +++ b/doc/rbd/rbd-encryption.rst @@ -0,0 +1,148 @@ +====================== + Image Encryption +====================== + +.. index:: Ceph Block Device; encryption + +Starting with the Pacific release, image-level encryption can be handled +internally by RBD clients. This means you can set a secret key that will be +used to encrypt a specific RBD image. This page describes the scope of the +RBD encryption feature. + +.. note:: + The ``krbd`` kernel module does not support encryption at this time. + +.. note:: + External tools (e.g. dm-crypt, QEMU) can be used as well to encrypt + an RBD image, and the feature set and limitation set for that use may be + different than described here. + +Encryption Format +================= + +By default, RBD images are not encrypted. To encrypt an RBD image, it needs to +be formatted to one of the supported encryption formats. The format operation +persists encryption metadata to the image. The encryption metadata usually +includes information such as the encryption format and version, cipher +algorithm and mode specification, as well as information used to secure the +encryption key. The encryption key itself is protected by a user-kept secret +(usually a passphrase), which is never persisted. The basic encryption format +operation will require specifying the encryption format and a secret. + +Some of the encryption metadata may be stored as part of the image data, +typically an encryption header will be written to the beginning of the raw +image data. This means that the effective image size of the encrypted image may +be lower than the raw image size. See the `Supported Formats`_ section for more +details. + +.. note:: + Currently only flat images (i.e. not cloned) can be formatted. + Clones of an encrypted image are inherently encrypted using the same format + and secret. + +.. note:: + Any data written to the image prior to its format may become unreadable, + though it may still occupy storage resources. + +.. note:: + Images with the `journal feature`_ enabled cannot be formatted and encrypted + by RBD clients. + +Encryption Load +================= + +Formatting an image is a necessary pre-requisite for enabling encryption. +However, formatted images will still be treated as raw unencrypted images by +all of the RBD APIs. In particular, an encrypted RBD image can be opened +by the same APIs as any other image, and raw unencrypted data can be +read / written. Such raw IOs may risk the integrity of the encryption format, +for example by overriding encryption metadata located at the beginning of the +image. + +In order to safely perform encrypted IO on the formatted image, an additional +*encryption load* operation should be applied after opening the image. The +encryption load operation requires supplying the encryption format and a secret +for unlocking the encryption key. Following a successful encryption load +operation, all IOs for the opened image will be encrypted / decrypted. +For a cloned image, this includes IOs for ancestor images as well. The +encryption key will be stored in-memory by the RBD client until the image is +closed. + +.. note:: + Once encryption has been loaded, no other encryption load / format + operations can be applied to the context of the opened image. + +.. note:: + Once encryption has been loaded, API calls for retrieving the image size + using the opened image context will return the effective image size. + +.. note:: + Encryption load can be automatically applied when mounting RBD images as + block devices via `rbd-nbd`_. + +Supported Formats +================= + +LUKS +~~~~~~~ + +Both LUKS1 and LUKS2 are supported. The data layout is fully compliant with the +LUKS specification. Thus, images formatted by RBD can be loaded using external +LUKS-supporting tools such as dm-crypt or QEMU. Furthermore, existing LUKS +data, created outside of RBD, can be imported (by copying the raw LUKS data +into the image) and loaded by RBD encryption. + +.. note:: + The LUKS formats are supported on Linux-based systems only. + +.. note:: + Currently, only AES-128 and AES-256 encryption algorithms are supported. + Additionally, xts-plain64 is currently the only supported encryption mode. + +To use the LUKS format, start by formatting the image:: + + $ rbd encryption format {pool-name}/{image-name} {luks1|luks2} {passphrase-file} [–cipher-alg {aes-128 | aes-256}] + +The encryption format operation generates a LUKS header and writes it to the +beginning of the image. The header is appended with a single keyslot holding a +randomly-generated encryption key, and is protected by the passphrase read from +`passphrase-file`. + +.. note:: + If the content of `passphrase-file` ends with a newline character, it will + be stripped off. + +By default, AES-256 in xts-plain64 mode (which is the current recommended mode, +and the usual default for other tools) will be used. The format operation +allows selecting AES-128 as well. Adding / removing passphrases is currently +not supported by RBD, but can be applied to the raw RBD data using compatible +tools such as cryptsetup. + +The LUKS header size can vary (upto 136MiB in LUKS2), but is usually upto +16MiB, depending on the version of `libcryptsetup` installed. For optimal +performance, the encryption format will set the data offset to be aligned with +the image object size. For example expect a minimum overhead of 8MiB if using +an imageconfigured with an 8MiB object size. + +In LUKS1, sectors, which are the minimal encryption units, are fixed at 512 +bytes. LUKS2 supports larger sectors, and for better performance we set +the default sector size to the maximum of 4KiB. Writes which are either smaller +than a sector, or are not aligned to a sector start, will trigger a guarded +read-modify-write chain on the client, with a considerable latency penalty. +A batch of such unaligned writes can lead to IO races which will further +deteriorate performance. Thus it is advisable to avoid using RBD encryption +in cases where incoming writes cannot be guaranteed to be sector-aligned. + +To mount a LUKS-encrypted image run:: + + $ rbd -p {pool-name} device map -t nbd -o encryption-format={luks1|luks2},encryption-passphrase-file={passphrase-file} + +Note that for security reasons, both the encryption format and encryption load +operations are CPU-intensive, and may take a few seconds to complete. For the +encryption operations of actual image IO, assuming AES-NI is enabled, +a relative small microseconds latency should be added, as well as a small +increase in CPU utilization. + +.. _journal feature: ../rbd-mirroring/#enable-image-journaling-feature +.. _Supported Formats: #supported-formats +.. _rbd-nbd: ../../man/8/rbd-nbd diff --git a/doc/rbd/rbd-exclusive-locks.rst b/doc/rbd/rbd-exclusive-locks.rst new file mode 100644 index 000000000..03609c74f --- /dev/null +++ b/doc/rbd/rbd-exclusive-locks.rst @@ -0,0 +1,86 @@ +.. _rbd-exclusive-locks: + +==================== + RBD Exclusive Locks +==================== + +.. index:: Ceph Block Device; RBD exclusive locks; exclusive-lock + +Exclusive locks are mechanisms designed to prevent multiple processes from +accessing the same Rados Block Device (RBD) in an uncoordinated fashion. +Exclusive locks are used heavily in virtualization (where they prevent VMs from +clobbering each other's writes) and in RBD mirroring (where they are a +prerequisite for journaling). + +By default, exclusive locks are enabled on newly created images. This default +can be overridden via the ``rbd_default_features`` configuration option or the +``--image-feature`` option for ``rbd create``. + +.. note:: + Many image features, including ``object-map`` and ``fast-diff``, depend upon + exclusive locking. Disabling the ``exclusive-lock`` feature will negatively + affect the performance of some operations. + +In order to ensure proper exclusive locking operations, any client using an RBD +image whose ``exclusive-lock`` feature is enabled must have a CephX identity +whose capabilities include ``profile rbd``. + +Exclusive locking is mostly transparent to the user. + +#. Whenever any ``librbd`` client process or kernel RBD client + starts using an RBD image on which exclusive locking has been + enabled, it obtains an exclusive lock on the image before the first + write. + +#. Whenever any such client process terminates gracefully, the process + relinquishes the lock automatically. + +#. This graceful termination enables another, subsequent, process to acquire + the lock and to write to the image. + +.. note:: + It is possible for two or more concurrently running processes to open the + image and to read from it. The client acquires the exclusive lock only when + attempting to write to the image. To disable transparent lock transitions + between multiple clients, the client must acquire the lock by using the + ``RBD_LOCK_MODE_EXCLUSIVE`` flag. + + +Blacklisting +============ + +Sometimes a client process (or, in case of a krbd client, a client node's +kernel) that previously held an exclusive lock on an image does not terminate +gracefully, but dies abruptly. This may be because the client process received +a ``KILL`` or ``ABRT`` signal, or because the client node underwent a hard +reboot or suffered a power failure. In cases like this, the exclusive lock is +never gracefully released. This means that any new process that starts and +attempts to use the device must break the previously held exclusive lock. + +However, a process (or kernel thread) may hang or merely lose network +connectivity to the Ceph cluster for some amount of time. In that case, +breaking the lock would be potentially catastrophic: the hung process or +connectivity issue could resolve itself and the original process might then +compete with one that started in the interim, thus accessing RBD data in an +uncoordinated and destructive manner. + +In the event that a lock cannot be acquired in the standard graceful manner, +the overtaking process not only breaks the lock but also blocklists the +previous lock holder. This is negotiated between the new client process and the +Ceph Monitor. + +* Upon receiving the blocklist request, the monitor instructs the relevant OSDs + to no longer serve requests from the old client process; +* after the associated OSD map update is complete, the new client can break the + previously held lock; +* after the new client has acquired the lock, it can commence writing + to the image. + +Blocklisting is thus a form of storage-level resource `fencing`_. + +In order for blocklisting to work, the client must have the ``osd +blocklist`` capability. This capability is included in the ``profile +rbd`` capability profile, which should be set generally on all Ceph +:ref:`client identities <user-management>` using RBD. + +.. _fencing: https://en.wikipedia.org/wiki/Fencing_(computing) diff --git a/doc/rbd/rbd-integrations.rst b/doc/rbd/rbd-integrations.rst new file mode 100644 index 000000000..50d788d53 --- /dev/null +++ b/doc/rbd/rbd-integrations.rst @@ -0,0 +1,15 @@ +========================================= + Ceph Block Device 3rd Party Integration +========================================= + +.. toctree:: + :maxdepth: 1 + + Kernel Modules <rbd-ko> + QEMU <qemu-rbd> + libvirt <libvirt> + Kubernetes <rbd-kubernetes> + OpenStack <rbd-openstack> + CloudStack <rbd-cloudstack> + LIO iSCSI Gateway <iscsi-overview> + Windows <rbd-windows> diff --git a/doc/rbd/rbd-ko.rst b/doc/rbd/rbd-ko.rst new file mode 100644 index 000000000..70c407839 --- /dev/null +++ b/doc/rbd/rbd-ko.rst @@ -0,0 +1,59 @@ +========================== + Kernel Module Operations +========================== + +.. index:: Ceph Block Device; kernel module + +.. important:: To use kernel module operations, you must have a running Ceph cluster. + +Get a List of Images +==================== + +To mount a block device image, first return a list of the images. :: + + rbd list + +Map a Block Device +================== + +Use ``rbd`` to map an image name to a kernel module. You must specify the +image name, the pool name, and the user name. ``rbd`` will load RBD kernel +module on your behalf if it's not already loaded. :: + + sudo rbd device map {pool-name}/{image-name} --id {user-name} + +For example:: + + sudo rbd device map rbd/myimage --id admin + +If you use `cephx`_ authentication, you must also specify a secret. It may come +from a keyring or a file containing the secret. :: + + sudo rbd device map rbd/myimage --id admin --keyring /path/to/keyring + sudo rbd device map rbd/myimage --id admin --keyfile /path/to/file + + +Show Mapped Block Devices +========================= + +To show block device images mapped to kernel modules with the ``rbd``, +specify ``device list`` arguments. :: + + rbd device list + + +Unmapping a Block Device +======================== + +To unmap a block device image with the ``rbd`` command, specify the +``device unmap`` arguments and the device name (i.e., by convention the +same as the block device image name). :: + + sudo rbd device unmap /dev/rbd/{poolname}/{imagename} + +For example:: + + sudo rbd device unmap /dev/rbd/rbd/foo + + +.. _cephx: ../../rados/operations/user-management/ diff --git a/doc/rbd/rbd-kubernetes.rst b/doc/rbd/rbd-kubernetes.rst new file mode 100644 index 000000000..caaf77d64 --- /dev/null +++ b/doc/rbd/rbd-kubernetes.rst @@ -0,0 +1,314 @@ +============================== + Block Devices and Kubernetes +============================== + +You may use Ceph Block Device images with Kubernetes v1.13 and later through +`ceph-csi`_, which dynamically provisions RBD images to back Kubernetes +`volumes`_ and maps these RBD images as block devices (optionally mounting +a file system contained within the image) on worker nodes running +`pods`_ that reference an RBD-backed volume. Ceph stripes block device images as +objects across the cluster, which means that large Ceph Block Device images have +better performance than a standalone server! + +To use Ceph Block Devices with Kubernetes v1.13 and higher, you must install +and configure ``ceph-csi`` within your Kubernetes environment. The following +diagram depicts the Kubernetes/Ceph technology stack. + +.. ditaa:: + +---------------------------------------------------+ + | Kubernetes | + +---------------------------------------------------+ + | ceph--csi | + +------------------------+--------------------------+ + | + | configures + v + +------------------------+ +------------------------+ + | | | rbd--nbd | + | Kernel Modules | +------------------------+ + | | | librbd | + +------------------------+-+------------------------+ + | RADOS Protocol | + +------------------------+-+------------------------+ + | OSDs | | Monitors | + +------------------------+ +------------------------+ + + +.. important:: + ``ceph-csi`` uses the RBD kernel modules by default which may not support all + Ceph `CRUSH tunables`_ or `RBD image features`_. + +Create a Pool +============= + +By default, Ceph block devices use the ``rbd`` pool. Create a pool for +Kubernetes volume storage. Ensure your Ceph cluster is running, then create +the pool. :: + + $ ceph osd pool create kubernetes + +See `Create a Pool`_ for details on specifying the number of placement groups +for your pools, and `Placement Groups`_ for details on the number of placement +groups you should set for your pools. + +A newly created pool must be initialized prior to use. Use the ``rbd`` tool +to initialize the pool:: + + $ rbd pool init kubernetes + +Configure ceph-csi +================== + +Setup Ceph Client Authentication +-------------------------------- + +Create a new user for Kubernetes and `ceph-csi`. Execute the following and +record the generated key:: + + $ ceph auth get-or-create client.kubernetes mon 'profile rbd' osd 'profile rbd pool=kubernetes' mgr 'profile rbd pool=kubernetes' + [client.kubernetes] + key = AQD9o0Fd6hQRChAAt7fMaSZXduT3NWEqylNpmg== + +Generate `ceph-csi` `ConfigMap` +------------------------------- + +The `ceph-csi` requires a `ConfigMap` object stored in Kubernetes to define the +the Ceph monitor addresses for the Ceph cluster. Collect both the Ceph cluster +unique `fsid` and the monitor addresses:: + + $ ceph mon dump + <...> + fsid b9127830-b0cc-4e34-aa47-9d1a2e9949a8 + <...> + 0: [v2:192.168.1.1:3300/0,v1:192.168.1.1:6789/0] mon.a + 1: [v2:192.168.1.2:3300/0,v1:192.168.1.2:6789/0] mon.b + 2: [v2:192.168.1.3:3300/0,v1:192.168.1.3:6789/0] mon.c + +.. note:: + ``ceph-csi`` currently only supports the `legacy V1 protocol`_. + +Generate a `csi-config-map.yaml` file similar to the example below, substituting +the `fsid` for "clusterID", and the monitor addresses for "monitors":: + + $ cat <<EOF > csi-config-map.yaml + --- + apiVersion: v1 + kind: ConfigMap + data: + config.json: |- + [ + { + "clusterID": "b9127830-b0cc-4e34-aa47-9d1a2e9949a8", + "monitors": [ + "192.168.1.1:6789", + "192.168.1.2:6789", + "192.168.1.3:6789" + ] + } + ] + metadata: + name: ceph-csi-config + EOF + +Once generated, store the new `ConfigMap` object in Kubernetes:: + + $ kubectl apply -f csi-config-map.yaml + +Generate `ceph-csi` cephx `Secret` +---------------------------------- + +`ceph-csi` requires the cephx credentials for communicating with the Ceph +cluster. Generate a `csi-rbd-secret.yaml` file similar to the example below, +using the newly created Kubernetes user id and cephx key:: + + $ cat <<EOF > csi-rbd-secret.yaml + --- + apiVersion: v1 + kind: Secret + metadata: + name: csi-rbd-secret + namespace: default + stringData: + userID: kubernetes + userKey: AQD9o0Fd6hQRChAAt7fMaSZXduT3NWEqylNpmg== + EOF + +Once generated, store the new `Secret` object in Kubernetes:: + + $ kubectl apply -f csi-rbd-secret.yaml + +Configure `ceph-csi` Plugins +---------------------------- + +Create the required `ServiceAccount` and RBAC `ClusterRole`/`ClusterRoleBinding` +Kubernetes objects. These objects do not necessarily need to be customized for +your Kubernetes environment and therefore can be used as-is from the `ceph-csi` +deployment YAMLs:: + + $ kubectl apply -f https://raw.githubusercontent.com/ceph/ceph-csi/master/deploy/rbd/kubernetes/csi-provisioner-rbac.yaml + $ kubectl apply -f https://raw.githubusercontent.com/ceph/ceph-csi/master/deploy/rbd/kubernetes/csi-nodeplugin-rbac.yaml + +Finally, create the `ceph-csi` provisioner and node plugins. With the +possible exception of the `ceph-csi` container release version, these objects do +not necessarily need to be customized for your Kubernetes environment and +therefore can be used as-is from the `ceph-csi` deployment YAMLs:: + + $ wget https://raw.githubusercontent.com/ceph/ceph-csi/master/deploy/rbd/kubernetes/csi-rbdplugin-provisioner.yaml + $ kubectl apply -f csi-rbdplugin-provisioner.yaml + $ wget https://raw.githubusercontent.com/ceph/ceph-csi/master/deploy/rbd/kubernetes/csi-rbdplugin.yaml + $ kubectl apply -f csi-rbdplugin.yaml + +.. important:: + The provisioner and node plugin YAMLs will, by default, pull the development + release of the `ceph-csi` container (quay.io/cephcsi/cephcsi:canary). + The YAMLs should be updated to use a release version container for + production workloads. + +Using Ceph Block Devices +======================== + +Create a `StorageClass` +----------------------- + +The Kubernetes `StorageClass` defines a class of storage. Multiple `StorageClass` +objects can be created to map to different quality-of-service levels (i.e. NVMe +vs HDD-based pools) and features. + +For example, to create a `ceph-csi` `StorageClass` that maps to the `kubernetes` +pool created above, the following YAML file can be used after ensuring that the +"clusterID" property matches your Ceph cluster's `fsid`:: + + $ cat <<EOF > csi-rbd-sc.yaml + --- + apiVersion: storage.k8s.io/v1 + kind: StorageClass + metadata: + name: csi-rbd-sc + provisioner: rbd.csi.ceph.com + parameters: + clusterID: b9127830-b0cc-4e34-aa47-9d1a2e9949a8 + pool: kubernetes + csi.storage.k8s.io/provisioner-secret-name: csi-rbd-secret + csi.storage.k8s.io/provisioner-secret-namespace: default + csi.storage.k8s.io/node-stage-secret-name: csi-rbd-secret + csi.storage.k8s.io/node-stage-secret-namespace: default + reclaimPolicy: Delete + mountOptions: + - discard + EOF + $ kubectl apply -f csi-rbd-sc.yaml + +Create a `PersistentVolumeClaim` +-------------------------------- + +A `PersistentVolumeClaim` is a request for abstract storage resources by a user. +The `PersistentVolumeClaim` would then be associated to a `Pod` resource to +provision a `PersistentVolume`, which would be backed by a Ceph block image. +An optional `volumeMode` can be included to select between a mounted file system +(default) or raw block device-based volume. + +Using `ceph-csi`, specifying `Filesystem` for `volumeMode` can support both +`ReadWriteOnce` and `ReadOnlyMany` `accessMode` claims, and specifying `Block` +for `volumeMode` can support `ReadWriteOnce`, `ReadWriteMany`, and +`ReadOnlyMany` `accessMode` claims. + +For example, to create a block-based `PersistentVolumeClaim` that utilizes +the `ceph-csi`-based `StorageClass` created above, the following YAML can be +used to request raw block storage from the `csi-rbd-sc` `StorageClass`:: + + $ cat <<EOF > raw-block-pvc.yaml + --- + apiVersion: v1 + kind: PersistentVolumeClaim + metadata: + name: raw-block-pvc + spec: + accessModes: + - ReadWriteOnce + volumeMode: Block + resources: + requests: + storage: 1Gi + storageClassName: csi-rbd-sc + EOF + $ kubectl apply -f raw-block-pvc.yaml + +The following demonstrates and example of binding the above +`PersistentVolumeClaim` to a `Pod` resource as a raw block device:: + + $ cat <<EOF > raw-block-pod.yaml + --- + apiVersion: v1 + kind: Pod + metadata: + name: pod-with-raw-block-volume + spec: + containers: + - name: fc-container + image: fedora:26 + command: ["/bin/sh", "-c"] + args: ["tail -f /dev/null"] + volumeDevices: + - name: data + devicePath: /dev/xvda + volumes: + - name: data + persistentVolumeClaim: + claimName: raw-block-pvc + EOF + $ kubectl apply -f raw-block-pod.yaml + +To create a file-system-based `PersistentVolumeClaim` that utilizes the +`ceph-csi`-based `StorageClass` created above, the following YAML can be used to +request a mounted file system (backed by an RBD image) from the `csi-rbd-sc` +`StorageClass`:: + + $ cat <<EOF > pvc.yaml + --- + apiVersion: v1 + kind: PersistentVolumeClaim + metadata: + name: rbd-pvc + spec: + accessModes: + - ReadWriteOnce + volumeMode: Filesystem + resources: + requests: + storage: 1Gi + storageClassName: csi-rbd-sc + EOF + $ kubectl apply -f pvc.yaml + +The following demonstrates and example of binding the above +`PersistentVolumeClaim` to a `Pod` resource as a mounted file system:: + + $ cat <<EOF > pod.yaml + --- + apiVersion: v1 + kind: Pod + metadata: + name: csi-rbd-demo-pod + spec: + containers: + - name: web-server + image: nginx + volumeMounts: + - name: mypvc + mountPath: /var/lib/www/html + volumes: + - name: mypvc + persistentVolumeClaim: + claimName: rbd-pvc + readOnly: false + EOF + $ kubectl apply -f pod.yaml + +.. _ceph-csi: https://github.com/ceph/ceph-csi/ +.. _volumes: https://kubernetes.io/docs/concepts/storage/volumes/ +.. _pods: https://kubernetes.io/docs/concepts/workloads/pods/pod-overview/ +.. _Create a Pool: ../../rados/operations/pools#createpool +.. _Placement Groups: ../../rados/operations/placement-groups +.. _CRUSH tunables: ../../rados/operations/crush-map/#tunables +.. _RBD image features: ../rbd-config-ref/#image-features +.. _legacy V1 protocol: ../../rados/configuration/msgr2/#address-formats diff --git a/doc/rbd/rbd-live-migration.rst b/doc/rbd/rbd-live-migration.rst new file mode 100644 index 000000000..c3e09193d --- /dev/null +++ b/doc/rbd/rbd-live-migration.rst @@ -0,0 +1,367 @@ +====================== + Image Live-Migration +====================== + +.. index:: Ceph Block Device; live-migration + +RBD images can be live-migrated between different pools within the same cluster; +between different image formats and layouts; or from external data sources. +When started, the source will be deep-copied to the destination image, pulling +all snapshot history while preserving the sparse allocation of data where +possible. + +By default, when live-migrating RBD images within the same Ceph cluster, the +source image will be marked read-only and all clients will instead redirect +IOs to the new target image. In addition, this mode can optionally preserve the +link to the source image's parent to preserve sparseness, or it can flatten the +image during the migration to remove the dependency on the source image's +parent. + +The live-migration process can also be used in an import-only mode where the +source image remains unmodified and the target image can be linked to an +external data source such as a backing file, HTTP(s) file, or S3 object. + +The live-migration copy process can safely run in the background while the new +target image is in use. There is currently a requirement to temporarily stop +using the source image before preparing a migration when not using the +import-only mode of operation. This helps to ensure that the client using the +image is updated to point to the new target image. + +.. note:: + Image live-migration requires the Ceph Nautilus release or later. Support for + external data sources requires the Ceph Pacific release of later. The + ``krbd`` kernel module does not support live-migration at this time. + + +.. ditaa:: + + +-------------+ +-------------+ + | {s} c999 | | {s} | + | Live | Target refers | Live | + | migration |<-------------*| migration | + | source | to Source | target | + | | | | + | (read only) | | (writable) | + +-------------+ +-------------+ + + Source Target + +The live-migration process is comprised of three steps: + +#. **Prepare Migration:** The initial step creates the new target image and + links the target image to the source. When not configured in the import-only + mode, the source image will also be linked to the target image and marked + read-only. + + Similar to `layered images`_, attempts to read uninitialized data extents + within the target image will internally redirect the read to the source + image, and writes to uninitialized extents within the target will internally + deep-copy the overlapping source image block to the target image. + + +#. **Execute Migration:** This is a background operation that deep-copies all + initialized blocks from the source image to the target. This step can be + run while clients are actively using the new target image. + + +#. **Finish Migration:** Once the background migration process has completed, + the migration can be committed or aborted. Committing the migration will + remove the cross-links between the source and target images, and will + remove the source image if not configured in the import-only mode. Aborting + the migration will remove the cross-links, and will remove the target image. + +Prepare Migration +================= + +The default live-migration process for images within the same Ceph cluster is +initiated by running the `rbd migration prepare` command, providing the source +and target images:: + + $ rbd migration prepare migration_source [migration_target] + +The `rbd migration prepare` command accepts all the same layout optionals as the +`rbd create` command, which allows changes to the immutable image on-disk +layout. The `migration_target` can be skipped if the goal is only to change the +on-disk layout, keeping the original image name. + +All clients using the source image must be stopped prior to preparing a +live-migration. The prepare step will fail if it finds any running clients with +the image open in read/write mode. Once the prepare step is complete, the +clients can be restarted using the new target image name. Attempting to restart +the clients using the source image name will result in failure. + +The `rbd status` command will show the current state of the live-migration:: + + $ rbd status migration_target + Watchers: none + Migration: + source: rbd/migration_source (5e2cba2f62e) + destination: rbd/migration_target (5e2ed95ed806) + state: prepared + +Note that the source image will be moved to the RBD trash to avoid mistaken +usage during the migration process:: + + $ rbd info migration_source + rbd: error opening image migration_source: (2) No such file or directory + $ rbd trash ls --all + 5e2cba2f62e migration_source + + +Prepare Import-Only Migration +============================= + +The import-only live-migration process is initiated by running the same +`rbd migration prepare` command, but adding the `--import-only` optional +and providing a JSON-encoded ``source-spec`` to describe how to access +the source image data. This ``source-spec`` can either be passed +directly via the `--source-spec` optional, or via a file or STDIN via the +`--source-spec-path` optional:: + + $ rbd migration prepare --import-only --source-spec "<JSON>" migration_target + +The `rbd migration prepare` command accepts all the same layout optionals as the +`rbd create` command. + +The `rbd status` command will show the current state of the live-migration:: + + $ rbd status migration_target + Watchers: none + Migration: + source: {"stream":{"file_path":"/mnt/image.raw","type":"file"},"type":"raw"} + destination: rbd/migration_target (ac69113dc1d7) + state: prepared + +The general format for the ``source-spec`` JSON is as follows:: + + { + "type": "<format-type>", + <format unique parameters> + "stream": { + "type": "<stream-type>", + <stream unique parameters> + } + } + +The following formats are currently supported: ``native``, ``qcow``, and +``raw``. The following streams are currently supported: ``file``, ``http``, and +``s3``. + +Formats +~~~~~~~ + +The ``native`` format can be used to describe a native RBD image within a +Ceph cluster as the source image. Its ``source-spec`` JSON is encoded +as follows:: + + { + "type": "native", + "pool_name": "<pool-name>", + ["pool_id": <pool-id>,] (optional alternative to "pool_name") + ["pool_namespace": "<pool-namespace",] (optional) + "image_name": "<image-name>", + ["image_id": "<image-id>",] (optional if image in trash) + "snap_name": "<snap-name>", + ["snap_id": "<snap-id>",] (optional alternative to "snap_name") + } + +Note that the ``native`` format does not include the ``stream`` object since +it utilizes native Ceph operations. For example, to import from the image +``rbd/ns1/image1@snap1``, the ``source-spec`` could be encoded as:: + + { + "type": "native", + "pool_name": "rbd", + "pool_namespace": "ns1", + "image_name": "image1", + "snap_name": "snap1" + } + +The ``qcow`` format can be used to describe a QCOW (QEMU copy-on-write) block +device. Both the QCOW (v1) and QCOW2 formats are currently supported with the +exception of advanced features such as compression, encryption, backing +files, and external data files. Support for these missing features may be added +in a future release. The ``qcow`` format data can be linked to any supported +stream source described below. For example, its base ``source-spec`` JSON is +encoded as follows:: + + { + "type": "qcow", + "stream": { + <stream unique parameters> + } + } + +The ``raw`` format can be used to describe a thick-provisioned, raw block device +export (i.e. `rbd export --export-format 1 <snap-spec>`). The ``raw`` format +data can be linked to any supported stream source described below. For example, +its base ``source-spec`` JSON is encoded as follows:: + + { + "type": "raw", + "stream": { + <stream unique parameters for HEAD, non-snapshot revision> + }, + "snapshots": [ + { + "type": "raw", + "name": "<snapshot-name>", + "stream": { + <stream unique parameters for snapshot> + } + }, + ] (optional oldest to newest ordering of snapshots) + } + +The inclusion of the ``snapshots`` array is optional and currently only supports +thick-provisioned ``raw`` snapshot exports. + +Additional formats such as RBD export-format v2 and RBD export-diff +snapshots will be added in a future release. + +Streams +~~~~~~~ + +The ``file`` stream can be used to import from a locally accessible POSIX file +source. Its ``source-spec`` JSON is encoded as follows:: + + { + <format unique parameters> + "stream": { + "type": "file", + "file_path": "<file-path>" + } + } + +For example, to import a raw-format image from a file located at +"/mnt/image.raw", its ``source-spec`` JSON is encoded as follows:: + + { + "type": "raw", + "stream": { + "type": "file", + "file_path": "/mnt/image.raw" + } + } + +The ``http`` stream can be used to import from a remote HTTP or HTTPS web +server. Its ``source-spec`` JSON is encoded as follows:: + + { + <format unique parameters> + "stream": { + "type": "http", + "url": "<url-path>" + } + } + +For example, to import a raw-format image from a file located at +``http://download.ceph.com/image.raw``, its ``source-spec`` JSON is encoded +as follows:: + + { + "type": "raw", + "stream": { + "type": "http", + "url": "http://download.ceph.com/image.raw" + } + } + +The ``s3`` stream can be used to import from a remote S3 bucket. Its +``source-spec`` JSON is encoded as follows:: + + { + <format unique parameters> + "stream": { + "type": "s3", + "url": "<url-path>", + "access_key": "<access-key>", + "secret_key": "<secret-key>" + } + } + +For example, to import a raw-format image from a file located at +`http://s3.ceph.com/bucket/image.raw`, its ``source-spec`` JSON is encoded +as follows:: + + { + "type": "raw", + "stream": { + "type": "s3", + "url": "http://s3.ceph.com/bucket/image.raw", + "access_key": "NX5QOQKC6BH2IDN8HC7A", + "secret_key": "LnEsqNNqZIpkzauboDcLXLcYaWwLQ3Kop0zAnKIn" + } + } + +.. note:: + The ``access_key`` and ``secret_key`` parameters support storing the keys in + the MON config-key store by prefixing the key values with ``config://`` + followed by the path in the MON config-key store to the value. Values can be + stored in the config-key store via ``ceph config-key set <key-path> <value>`` + (e.g. ``ceph config-key set rbd/s3/access_key NX5QOQKC6BH2IDN8HC7A``). + +Execute Migration +================= + +After preparing the live-migration, the image blocks from the source image +must be copied to the target image. This is accomplished by running the +`rbd migration execute` command:: + + $ rbd migration execute migration_target + Image migration: 100% complete...done. + +The `rbd status` command will also provide feedback on the progress of the +migration block deep-copy process:: + + $ rbd status migration_target + Watchers: + watcher=1.2.3.4:0/3695551461 client.123 cookie=123 + Migration: + source: rbd/migration_source (5e2cba2f62e) + destination: rbd/migration_target (5e2ed95ed806) + state: executing (32% complete) + + +Commit Migration +================ + +Once the live-migration has completed deep-copying all data blocks from the +source image to the target, the migration can be committed:: + + $ rbd status migration_target + Watchers: none + Migration: + source: rbd/migration_source (5e2cba2f62e) + destination: rbd/migration_target (5e2ed95ed806) + state: executed + $ rbd migration commit migration_target + Commit image migration: 100% complete...done. + +If the `migration_source` image is a parent of one or more clones, the `--force` +option will need to be specified after ensuring all descendent clone images are +not in use. + +Committing the live-migration will remove the cross-links between the source +and target images, and will remove the source image:: + + $ rbd trash list --all + + +Abort Migration +=============== + +If you wish to revert the prepare or execute step, run the `rbd migration abort` +command to revert the migration process:: + + $ rbd migration abort migration_target + Abort image migration: 100% complete...done. + +Aborting the migration will result in the target image being deleted and access +to the original source image being restored:: + + $ rbd ls + migration_source + + +.. _layered images: ../rbd-snapshot/#layering diff --git a/doc/rbd/rbd-mirroring.rst b/doc/rbd/rbd-mirroring.rst new file mode 100644 index 000000000..d5d1191d6 --- /dev/null +++ b/doc/rbd/rbd-mirroring.rst @@ -0,0 +1,529 @@ +=============== + RBD Mirroring +=============== + +.. index:: Ceph Block Device; mirroring + +RBD images can be asynchronously mirrored between two Ceph clusters. This +capability is available in two modes: + +* **Journal-based**: This mode uses the RBD journaling image feature to ensure + point-in-time, crash-consistent replication between clusters. Every write to + the RBD image is first recorded to the associated journal before modifying the + actual image. The remote cluster will read from this associated journal and + replay the updates to its local copy of the image. Since each write to the + RBD image will result in two writes to the Ceph cluster, expect write + latencies to nearly double while using the RBD journaling image feature. + +* **Snapshot-based**: This mode uses periodically scheduled or manually + created RBD image mirror-snapshots to replicate crash-consistent RBD images + between clusters. The remote cluster will determine any data or metadata + updates between two mirror-snapshots and copy the deltas to its local copy of + the image. With the help of the RBD ``fast-diff`` image feature, updated data + blocks can be quickly determined without the need to scan the full RBD image. + Since this mode is not as fine-grained as journaling, the complete delta + between two snapshots will need to be synced prior to use during a failover + scenario. Any partially applied set of deltas will be rolled back at moment + of failover. + +.. note:: journal-based mirroring requires the Ceph Jewel release or later; + snapshot-based mirroring requires the Ceph Octopus release or later. + +Mirroring is configured on a per-pool basis within peer clusters and can be +configured on a specific subset of images within the pool. You can also mirror +all images within a given pool when using journal-based +mirroring. Mirroring is configured using the ``rbd`` command. The +``rbd-mirror`` daemon is responsible for pulling image updates from the remote +peer cluster and applying them to the image within the local cluster. + +Depending on the desired needs for replication, RBD mirroring can be configured +for either one- or two-way replication: + +* **One-way Replication**: When data is only mirrored from a primary cluster to + a secondary cluster, the ``rbd-mirror`` daemon runs only on the secondary + cluster. + +* **Two-way Replication**: When data is mirrored from primary images on one + cluster to non-primary images on another cluster (and vice-versa), the + ``rbd-mirror`` daemon runs on both clusters. + +.. important:: Each instance of the ``rbd-mirror`` daemon must be able to + connect to both the local and remote Ceph clusters simultaneously (i.e. + all monitor and OSD hosts). Additionally, the network must have sufficient + bandwidth between the two data centers to handle mirroring workload. + +Pool Configuration +================== + +The following procedures demonstrate how to perform the basic administrative +tasks to configure mirroring using the ``rbd`` command. Mirroring is +configured on a per-pool basis. + +These pool configuration steps should be performed on both peer clusters. These +procedures assume that both clusters, named "site-a" and "site-b", are accessible +from a single host for clarity. + +See the `rbd`_ manpage for additional details of how to connect to different +Ceph clusters. + +.. note:: The cluster name in the following examples corresponds to a Ceph + configuration file of the same name (e.g. /etc/ceph/site-b.conf). See the + `ceph-conf`_ documentation for how to configure multiple clusters. Note + that ``rbd-mirror`` does **not** require the source and destination clusters + to have unique internal names; both can and should call themselves ``ceph``. + The config `files` that ``rbd-mirror`` needs for local and remote clusters + can be named arbitrarily, and containerizing the daemon is one strategy + for maintaining them outside of ``/etc/ceph`` to avoid confusion. + +Enable Mirroring +---------------- + +To enable mirroring on a pool with ``rbd``, issue the ``mirror pool enable`` +subcommand with the pool name, and the mirroring mode:: + + rbd mirror pool enable {pool-name} {mode} + +The mirroring mode can either be ``image`` or ``pool``: + +* **image**: When configured in ``image`` mode, mirroring must + `explicitly enabled`_ on each image. +* **pool** (default): When configured in ``pool`` mode, all images in the pool + with the journaling feature enabled are mirrored. + +For example:: + + $ rbd --cluster site-a mirror pool enable image-pool image + $ rbd --cluster site-b mirror pool enable image-pool image + +Disable Mirroring +----------------- + +To disable mirroring on a pool with ``rbd``, specify the ``mirror pool disable`` +command and the pool name:: + + rbd mirror pool disable {pool-name} + +When mirroring is disabled on a pool in this way, mirroring will also be +disabled on any images (within the pool) for which mirroring was enabled +explicitly. + +For example:: + + $ rbd --cluster site-a mirror pool disable image-pool + $ rbd --cluster site-b mirror pool disable image-pool + +Bootstrap Peers +--------------- + +In order for the ``rbd-mirror`` daemon to discover its peer cluster, the peer +must be registered and a user account must be created. +This process can be automated with ``rbd`` and the +``mirror pool peer bootstrap create`` and ``mirror pool peer bootstrap import`` +commands. + +To manually create a new bootstrap token with ``rbd``, issue the +``mirror pool peer bootstrap create`` subcommand, a pool name, and an +optional friendly site name to describe the local cluster:: + + rbd mirror pool peer bootstrap create [--site-name {local-site-name}] {pool-name} + +The output of ``mirror pool peer bootstrap create`` will be a token that should +be provided to the ``mirror pool peer bootstrap import`` command. For example, +on site-a:: + + $ rbd --cluster site-a mirror pool peer bootstrap create --site-name site-a image-pool + eyJmc2lkIjoiOWY1MjgyZGItYjg5OS00NTk2LTgwOTgtMzIwYzFmYzM5NmYzIiwiY2xpZW50X2lkIjoicmJkLW1pcnJvci1wZWVyIiwia2V5IjoiQVFBUnczOWQwdkhvQmhBQVlMM1I4RmR5dHNJQU50bkFTZ0lOTVE9PSIsIm1vbl9ob3N0IjoiW3YyOjE5Mi4xNjguMS4zOjY4MjAsdjE6MTkyLjE2OC4xLjM6NjgyMV0ifQ== + +To manually import the bootstrap token created by another cluster with ``rbd``, +specify the ``mirror pool peer bootstrap import`` command, the pool name, a file +path to the created token (or '-' to read from standard input), along with an +optional friendly site name to describe the local cluster and a mirroring +direction (defaults to rx-tx for bidirectional mirroring, but can also be set +to rx-only for unidirectional mirroring):: + + rbd mirror pool peer bootstrap import [--site-name {local-site-name}] [--direction {rx-only or rx-tx}] {pool-name} {token-path} + +For example, on site-b:: + + $ cat <<EOF > token + eyJmc2lkIjoiOWY1MjgyZGItYjg5OS00NTk2LTgwOTgtMzIwYzFmYzM5NmYzIiwiY2xpZW50X2lkIjoicmJkLW1pcnJvci1wZWVyIiwia2V5IjoiQVFBUnczOWQwdkhvQmhBQVlMM1I4RmR5dHNJQU50bkFTZ0lOTVE9PSIsIm1vbl9ob3N0IjoiW3YyOjE5Mi4xNjguMS4zOjY4MjAsdjE6MTkyLjE2OC4xLjM6NjgyMV0ifQ== + EOF + $ rbd --cluster site-b mirror pool peer bootstrap import --site-name site-b image-pool token + +Add Cluster Peer Manually +------------------------- + +Cluster peers can be specified manually if desired or if the above bootstrap +commands are not available with the currently installed Ceph release. + +The remote ``rbd-mirror`` daemon will need access to the local cluster to +perform mirroring. A new local Ceph user should be created for the remote +daemon to use. To `create a Ceph user`_, with ``ceph`` specify the +``auth get-or-create`` command, user name, monitor caps, and OSD caps:: + + ceph auth get-or-create client.rbd-mirror-peer mon 'profile rbd' osd 'profile rbd' + +The resulting keyring should be copied to the other cluster's ``rbd-mirror`` +daemon hosts if not using the Ceph monitor ``config-key`` store described below. + +To manually add a mirroring peer Ceph cluster with ``rbd``, specify the +``mirror pool peer add`` command, the pool name, and a cluster specification:: + + rbd mirror pool peer add {pool-name} {client-name}@{cluster-name} + +For example:: + + $ rbd --cluster site-a mirror pool peer add image-pool client.rbd-mirror-peer@site-b + $ rbd --cluster site-b mirror pool peer add image-pool client.rbd-mirror-peer@site-a + +By default, the ``rbd-mirror`` daemon needs to have access to a Ceph +configuration file located at ``/etc/ceph/{cluster-name}.conf`` that provides +the addresses of the peer cluster's monitors, in addition to a keyring for +``{client-name}`` located in the default or configured keyring search paths +(e.g. ``/etc/ceph/{cluster-name}.{client-name}.keyring``). + +Alternatively, the peer cluster's monitor and/or client key can be securely +stored within the local Ceph monitor ``config-key`` store. To specify the +peer cluster connection attributes when adding a mirroring peer, use the +``--remote-mon-host`` and ``--remote-key-file`` optionals. For example:: + + $ cat <<EOF > remote-key-file + AQAeuZdbMMoBChAAcj++/XUxNOLFaWdtTREEsw== + EOF + $ rbd --cluster site-a mirror pool peer add image-pool client.rbd-mirror-peer@site-b --remote-mon-host 192.168.1.1,192.168.1.2 --remote-key-file remote-key-file + $ rbd --cluster site-a mirror pool info image-pool --all + Mode: pool + Peers: + UUID NAME CLIENT MON_HOST KEY + 587b08db-3d33-4f32-8af8-421e77abb081 site-b client.rbd-mirror-peer 192.168.1.1,192.168.1.2 AQAeuZdbMMoBChAAcj++/XUxNOLFaWdtTREEsw== + +Remove Cluster Peer +------------------- + +To remove a mirroring peer Ceph cluster with ``rbd``, specify the +``mirror pool peer remove`` command, the pool name, and the peer UUID +(available from the ``rbd mirror pool info`` command):: + + rbd mirror pool peer remove {pool-name} {peer-uuid} + +For example:: + + $ rbd --cluster site-a mirror pool peer remove image-pool 55672766-c02b-4729-8567-f13a66893445 + $ rbd --cluster site-b mirror pool peer remove image-pool 60c0e299-b38f-4234-91f6-eed0a367be08 + +Data Pools +---------- + +When creating images in the destination cluster, ``rbd-mirror`` selects a data +pool as follows: + +#. If the destination cluster has a default data pool configured (with the + ``rbd_default_data_pool`` configuration option), it will be used. +#. Otherwise, if the source image uses a separate data pool, and a pool with the + same name exists on the destination cluster, that pool will be used. +#. If neither of the above is true, no data pool will be set. + +Image Configuration +=================== + +Unlike pool configuration, image configuration only needs to be performed +against a single mirroring peer Ceph cluster. + +Mirrored RBD images are designated as either primary or non-primary. This is a +property of the image and not the pool. Images that are designated as +non-primary cannot be modified. + +Images are automatically promoted to primary when mirroring is first enabled on +an image (either implicitly if the pool mirror mode was ``pool`` and the image +has the journaling image feature enabled, or `explicitly enabled`_ by the +``rbd`` command if the pool mirror mode was ``image``). + +Enable Image Mirroring +---------------------- + +If mirroring is configured in ``image`` mode for the image's pool, then it +is necessary to explicitly enable mirroring for each image within the pool. +To enable mirroring for a specific image with ``rbd``, specify the +``mirror image enable`` command along with the pool, image name, and mode:: + + rbd mirror image enable {pool-name}/{image-name} {mode} + +The mirror image mode can either be ``journal`` or ``snapshot``: + +* **journal** (default): When configured in ``journal`` mode, mirroring will + utilize the RBD journaling image feature to replicate the image contents. If + the RBD journaling image feature is not yet enabled on the image, it will be + automatically enabled. + +* **snapshot**: When configured in ``snapshot`` mode, mirroring will utilize + RBD image mirror-snapshots to replicate the image contents. Once enabled, an + initial mirror-snapshot will automatically be created. Additional RBD image + `mirror-snapshots`_ can be created by the ``rbd`` command. + +For example:: + + $ rbd --cluster site-a mirror image enable image-pool/image-1 snapshot + $ rbd --cluster site-a mirror image enable image-pool/image-2 journal + +Enable Image Journaling Feature +------------------------------- + +RBD journal-based mirroring uses the RBD image journaling feature to ensure that +the replicated image always remains crash-consistent. When using the ``image`` +mirroring mode, the journaling feature will be automatically enabled when +mirroring is enabled on the image. When using the ``pool`` mirroring mode, +before an image can be mirrored to a peer cluster, the RBD image journaling +feature must be enabled. The feature can be enabled at image creation time by +providing the ``--image-feature exclusive-lock,journaling`` option to the +``rbd`` command. + +Alternatively, the journaling feature can be dynamically enabled on +pre-existing RBD images. To enable journaling with ``rbd``, specify +the ``feature enable`` command, the pool and image name, and the feature name:: + + rbd feature enable {pool-name}/{image-name} {feature-name} + +For example:: + + $ rbd --cluster site-a feature enable image-pool/image-1 journaling + +.. note:: The journaling feature is dependent on the exclusive-lock feature. If + the exclusive-lock feature is not already enabled, it should be enabled prior + to enabling the journaling feature. + +.. tip:: You can enable journaling on all new images by default by adding + ``rbd default features = 125`` to your Ceph configuration file. + +.. tip:: ``rbd-mirror`` tunables are set by default to values suitable for + mirroring an entire pool. When using ``rbd-mirror`` to migrate single + volumes been clusters you may achieve substantial performance gains + by setting ``rbd_mirror_journal_max_fetch_bytes=33554432`` and + ``rbd_journal_max_payload_bytes=8388608`` within the ``[client]`` config + section of the local or centralized configuration. Note that these + settings may allow ``rbd-mirror`` to present a substantial write workload + to the destination cluster: monitor cluster performance closely during + migrations and test carefuly before running multiple migrations in parallel. + +Create Image Mirror-Snapshots +----------------------------- + +When using snapshot-based mirroring, mirror-snapshots will need to be created +whenever it is desired to mirror the changed contents of the RBD image. To +create a mirror-snapshot manually with ``rbd``, specify the +``mirror image snapshot`` command along with the pool and image name:: + + rbd mirror image snapshot {pool-name}/{image-name} + +For example:: + + $ rbd --cluster site-a mirror image snapshot image-pool/image-1 + +By default up to ``5`` mirror-snapshots will be created per-image. The most +recent mirror-snapshot is automatically pruned if the limit is reached. +The limit can be overridden via the ``rbd_mirroring_max_mirroring_snapshots`` +configuration option if required. Additionally, mirror-snapshots are +automatically deleted when the image is removed or when mirroring is disabled. + +Mirror-snapshots can also be automatically created on a periodic basis if +mirror-snapshot schedules are defined. The mirror-snapshot can be scheduled +globally, per-pool, or per-image levels. Multiple mirror-snapshot schedules can +be defined at any level, but only the most-specific snapshot schedules that +match an individual mirrored image will run. + +To create a mirror-snapshot schedule with ``rbd``, specify the +``mirror snapshot schedule add`` command along with an optional pool or +image name; interval; and optional start time:: + + rbd mirror snapshot schedule add [--pool {pool-name}] [--image {image-name}] {interval} [{start-time}] + +The ``interval`` can be specified in days, hours, or minutes using ``d``, ``h``, +``m`` suffix respectively. The optional ``start-time`` can be specified using +the ISO 8601 time format. For example:: + + $ rbd --cluster site-a mirror snapshot schedule add --pool image-pool 24h 14:00:00-05:00 + $ rbd --cluster site-a mirror snapshot schedule add --pool image-pool --image image1 6h + +To remove a mirror-snapshot schedules with ``rbd``, specify the +``mirror snapshot schedule remove`` command with options that match the +corresponding ``add`` schedule command. + +To list all snapshot schedules for a specific level (global, pool, or image) +with ``rbd``, specify the ``mirror snapshot schedule ls`` command along with +an optional pool or image name. Additionally, the ``--recursive`` option can +be specified to list all schedules at the specified level and below. For +example:: + + $ rbd --cluster site-a mirror schedule ls --pool image-pool --recursive + POOL NAMESPACE IMAGE SCHEDULE + image-pool - - every 1d starting at 14:00:00-05:00 + image-pool image1 every 6h + +To view the status for when the next snapshots will be created for +snapshot-based mirroring RBD images with ``rbd``, specify the +``mirror snapshot schedule status`` command along with an optional pool or +image name:: + + rbd mirror snapshot schedule status [--pool {pool-name}] [--image {image-name}] + +For example:: + + $ rbd --cluster site-a mirror schedule status + SCHEDULE TIME IMAGE + 2020-02-26 18:00:00 image-pool/image1 + +Disable Image Mirroring +----------------------- + +To disable mirroring for a specific image with ``rbd``, specify the +``mirror image disable`` command along with the pool and image name:: + + rbd mirror image disable {pool-name}/{image-name} + +For example:: + + $ rbd --cluster site-a mirror image disable image-pool/image-1 + +Image Promotion and Demotion +---------------------------- + +In a failover scenario where the primary designation needs to be moved to the +image in the peer Ceph cluster, access to the primary image should be stopped +(e.g. power down the VM or remove the associated drive from a VM), demote the +current primary image, promote the new primary image, and resume access to the +image on the alternate cluster. + +.. note:: RBD only provides the necessary tools to facilitate an orderly + failover of an image. An external mechanism is required to coordinate the + full failover process (e.g. closing the image before demotion). + +To demote a specific image to non-primary with ``rbd``, specify the +``mirror image demote`` command along with the pool and image name:: + + rbd mirror image demote {pool-name}/{image-name} + +For example:: + + $ rbd --cluster site-a mirror image demote image-pool/image-1 + +To demote all primary images within a pool to non-primary with ``rbd``, specify +the ``mirror pool demote`` command along with the pool name:: + + rbd mirror pool demote {pool-name} + +For example:: + + $ rbd --cluster site-a mirror pool demote image-pool + +To promote a specific image to primary with ``rbd``, specify the +``mirror image promote`` command along with the pool and image name:: + + rbd mirror image promote [--force] {pool-name}/{image-name} + +For example:: + + $ rbd --cluster site-b mirror image promote image-pool/image-1 + +To promote all non-primary images within a pool to primary with ``rbd``, specify +the ``mirror pool promote`` command along with the pool name:: + + rbd mirror pool promote [--force] {pool-name} + +For example:: + + $ rbd --cluster site-a mirror pool promote image-pool + +.. tip:: Since the primary / non-primary status is per-image, it is possible to + have two clusters split the IO load and stage failover / failback. + +.. note:: Promotion can be forced using the ``--force`` option. Forced + promotion is needed when the demotion cannot be propagated to the peer + Ceph cluster (e.g. Ceph cluster failure, communication outage). This will + result in a split-brain scenario between the two peers and the image will no + longer be in-sync until a `force resync command`_ is issued. + +Force Image Resync +------------------ + +If a split-brain event is detected by the ``rbd-mirror`` daemon, it will not +attempt to mirror the affected image until corrected. To resume mirroring for an +image, first `demote the image`_ determined to be out-of-date and then request a +resync to the primary image. To request an image resync with ``rbd``, specify +the ``mirror image resync`` command along with the pool and image name:: + + rbd mirror image resync {pool-name}/{image-name} + +For example:: + + $ rbd mirror image resync image-pool/image-1 + +.. note:: The ``rbd`` command only flags the image as requiring a resync. The + local cluster's ``rbd-mirror`` daemon process is responsible for performing + the resync asynchronously. + +Mirror Status +============= + +The peer cluster replication status is stored for every primary mirrored image. +This status can be retrieved using the ``mirror image status`` and +``mirror pool status`` commands. + +To request the mirror image status with ``rbd``, specify the +``mirror image status`` command along with the pool and image name:: + + rbd mirror image status {pool-name}/{image-name} + +For example:: + + $ rbd mirror image status image-pool/image-1 + +To request the mirror pool summary status with ``rbd``, specify the +``mirror pool status`` command along with the pool name:: + + rbd mirror pool status {pool-name} + +For example:: + + $ rbd mirror pool status image-pool + +.. note:: Adding ``--verbose`` option to the ``mirror pool status`` command will + additionally output status details for every mirroring image in the pool. + +rbd-mirror Daemon +================= + +The two ``rbd-mirror`` daemons are responsible for watching image journals on +the remote, peer cluster and replaying the journal events against the local +cluster. The RBD image journaling feature records all modifications to the +image in the order they occur. This ensures that a crash-consistent mirror of +the remote image is available locally. + +The ``rbd-mirror`` daemon is available within the optional ``rbd-mirror`` +distribution package. + +.. important:: Each ``rbd-mirror`` daemon requires the ability to connect + to both clusters simultaneously. +.. warning:: Pre-Luminous releases: only run a single ``rbd-mirror`` daemon per + Ceph cluster. + +Each ``rbd-mirror`` daemon should use a unique Ceph user ID. To +`create a Ceph user`_, with ``ceph`` specify the ``auth get-or-create`` +command, user name, monitor caps, and OSD caps:: + + ceph auth get-or-create client.rbd-mirror.{unique id} mon 'profile rbd-mirror' osd 'profile rbd' + +The ``rbd-mirror`` daemon can be managed by ``systemd`` by specifying the user +ID as the daemon instance:: + + systemctl enable ceph-rbd-mirror@rbd-mirror.{unique id} + +The ``rbd-mirror`` can also be run in foreground by ``rbd-mirror`` command:: + + rbd-mirror -f --log-file={log_path} + +.. _rbd: ../../man/8/rbd +.. _ceph-conf: ../../rados/configuration/ceph-conf/#running-multiple-clusters +.. _explicitly enabled: #enable-image-mirroring +.. _force resync command: #force-image-resync +.. _demote the image: #image-promotion-and-demotion +.. _create a Ceph user: ../../rados/operations/user-management#add-a-user +.. _mirror-snapshots: #create-image-mirror-snapshots diff --git a/doc/rbd/rbd-openstack.rst b/doc/rbd/rbd-openstack.rst new file mode 100644 index 000000000..3f1b85f30 --- /dev/null +++ b/doc/rbd/rbd-openstack.rst @@ -0,0 +1,395 @@ +============================= + Block Devices and OpenStack +============================= + +.. index:: Ceph Block Device; OpenStack + +You can attach Ceph Block Device images to OpenStack instances through ``libvirt``, +which configures the QEMU interface to ``librbd``. Ceph stripes block volumes +across multiple OSDs within the cluster, which means that large volumes can +realize better performance than local drives on a standalone server! + +To use Ceph Block Devices with OpenStack, you must install QEMU, ``libvirt``, +and OpenStack first. We recommend using a separate physical node for your +OpenStack installation. OpenStack recommends a minimum of 8GB of RAM and a +quad-core processor. The following diagram depicts the OpenStack/Ceph +technology stack. + + +.. ditaa:: + + +---------------------------------------------------+ + | OpenStack | + +---------------------------------------------------+ + | libvirt | + +------------------------+--------------------------+ + | + | configures + v + +---------------------------------------------------+ + | QEMU | + +---------------------------------------------------+ + | librbd | + +---------------------------------------------------+ + | librados | + +------------------------+-+------------------------+ + | OSDs | | Monitors | + +------------------------+ +------------------------+ + +.. important:: To use Ceph Block Devices with OpenStack, you must have + access to a running Ceph Storage Cluster. + +Three parts of OpenStack integrate with Ceph's block devices: + +- **Images**: OpenStack Glance manages images for VMs. Images are immutable. + OpenStack treats images as binary blobs and downloads them accordingly. + +- **Volumes**: Volumes are block devices. OpenStack uses volumes to boot VMs, + or to attach volumes to running VMs. OpenStack manages volumes using + Cinder services. + +- **Guest Disks**: Guest disks are guest operating system disks. By default, + when you boot a virtual machine, its disk appears as a file on the file system + of the hypervisor (usually under ``/var/lib/nova/instances/<uuid>/``). Prior + to OpenStack Havana, the only way to boot a VM in Ceph was to use the + boot-from-volume functionality of Cinder. However, now it is possible to boot + every virtual machine inside Ceph directly without using Cinder, which is + advantageous because it allows you to perform maintenance operations easily + with the live-migration process. Additionally, if your hypervisor dies it is + also convenient to trigger ``nova evacuate`` and reinstate the virtual machine + elsewhere almost seamlessly. In doing so, + :ref:`exclusive locks <rbd-exclusive-locks>` prevent multiple + compute nodes from concurrently accessing the guest disk. + + +You can use OpenStack Glance to store images as Ceph Block Devices, and you +can use Cinder to boot a VM using a copy-on-write clone of an image. + +The instructions below detail the setup for Glance, Cinder and Nova, although +they do not have to be used together. You may store images in Ceph block devices +while running VMs using a local disk, or vice versa. + +.. important:: Using QCOW2 for hosting a virtual machine disk is NOT recommended. + If you want to boot virtual machines in Ceph (ephemeral backend or boot + from volume), please use the ``raw`` image format within Glance. + +.. index:: pools; OpenStack + +Create a Pool +============= + +By default, Ceph block devices live within the ``rbd`` pool. You may use any +suitable pool by specifying it explicitly. We recommend creating a pool for +Cinder and a pool for Glance. Ensure your Ceph cluster is running, then create the pools. :: + + ceph osd pool create volumes + ceph osd pool create images + ceph osd pool create backups + ceph osd pool create vms + +See `Create a Pool`_ for detail on specifying the number of placement groups for +your pools, and `Placement Groups`_ for details on the number of placement +groups you should set for your pools. + +Newly created pools must be initialized prior to use. Use the ``rbd`` tool +to initialize the pools:: + + rbd pool init volumes + rbd pool init images + rbd pool init backups + rbd pool init vms + +.. _Create a Pool: ../../rados/operations/pools#createpool +.. _Placement Groups: ../../rados/operations/placement-groups + + +Configure OpenStack Ceph Clients +================================ + +The nodes running ``glance-api``, ``cinder-volume``, ``nova-compute`` and +``cinder-backup`` act as Ceph clients. Each requires the ``ceph.conf`` file:: + + ssh {your-openstack-server} sudo tee /etc/ceph/ceph.conf </etc/ceph/ceph.conf + + +Install Ceph client packages +---------------------------- + +On the ``glance-api`` node, you will need the Python bindings for ``librbd``:: + + sudo apt-get install python-rbd + sudo yum install python-rbd + +On the ``nova-compute``, ``cinder-backup`` and on the ``cinder-volume`` node, +use both the Python bindings and the client command line tools:: + + sudo apt-get install ceph-common + sudo yum install ceph-common + + +Setup Ceph Client Authentication +-------------------------------- + +If you have `cephx authentication`_ enabled, create a new user for Nova/Cinder +and Glance. Execute the following:: + + ceph auth get-or-create client.glance mon 'profile rbd' osd 'profile rbd pool=images' mgr 'profile rbd pool=images' + ceph auth get-or-create client.cinder mon 'profile rbd' osd 'profile rbd pool=volumes, profile rbd pool=vms, profile rbd-read-only pool=images' mgr 'profile rbd pool=volumes, profile rbd pool=vms' + ceph auth get-or-create client.cinder-backup mon 'profile rbd' osd 'profile rbd pool=backups' mgr 'profile rbd pool=backups' + +Add the keyrings for ``client.cinder``, ``client.glance``, and +``client.cinder-backup`` to the appropriate nodes and change their ownership:: + + ceph auth get-or-create client.glance | ssh {your-glance-api-server} sudo tee /etc/ceph/ceph.client.glance.keyring + ssh {your-glance-api-server} sudo chown glance:glance /etc/ceph/ceph.client.glance.keyring + ceph auth get-or-create client.cinder | ssh {your-volume-server} sudo tee /etc/ceph/ceph.client.cinder.keyring + ssh {your-cinder-volume-server} sudo chown cinder:cinder /etc/ceph/ceph.client.cinder.keyring + ceph auth get-or-create client.cinder-backup | ssh {your-cinder-backup-server} sudo tee /etc/ceph/ceph.client.cinder-backup.keyring + ssh {your-cinder-backup-server} sudo chown cinder:cinder /etc/ceph/ceph.client.cinder-backup.keyring + +Nodes running ``nova-compute`` need the keyring file for the ``nova-compute`` +process:: + + ceph auth get-or-create client.cinder | ssh {your-nova-compute-server} sudo tee /etc/ceph/ceph.client.cinder.keyring + +They also need to store the secret key of the ``client.cinder`` user in +``libvirt``. The libvirt process needs it to access the cluster while attaching +a block device from Cinder. + +Create a temporary copy of the secret key on the nodes running +``nova-compute``:: + + ceph auth get-key client.cinder | ssh {your-compute-node} tee client.cinder.key + +Then, on the compute nodes, add the secret key to ``libvirt`` and remove the +temporary copy of the key:: + + uuidgen + 457eb676-33da-42ec-9a8c-9293d545c337 + + cat > secret.xml <<EOF + <secret ephemeral='no' private='no'> + <uuid>457eb676-33da-42ec-9a8c-9293d545c337</uuid> + <usage type='ceph'> + <name>client.cinder secret</name> + </usage> + </secret> + EOF + sudo virsh secret-define --file secret.xml + Secret 457eb676-33da-42ec-9a8c-9293d545c337 created + sudo virsh secret-set-value --secret 457eb676-33da-42ec-9a8c-9293d545c337 --base64 $(cat client.cinder.key) && rm client.cinder.key secret.xml + +Save the uuid of the secret for configuring ``nova-compute`` later. + +.. important:: You don't necessarily need the UUID on all the compute nodes. + However from a platform consistency perspective, it's better to keep the + same UUID. + +.. _cephx authentication: ../../rados/configuration/auth-config-ref/#enabling-disabling-cephx + + +Configure OpenStack to use Ceph +=============================== + +Configuring Glance +------------------ + +Glance can use multiple back ends to store images. To use Ceph block devices by +default, configure Glance like the following. + + +Kilo and after +~~~~~~~~~~~~~~ + +Edit ``/etc/glance/glance-api.conf`` and add under the ``[glance_store]`` section:: + + [glance_store] + stores = rbd + default_store = rbd + rbd_store_pool = images + rbd_store_user = glance + rbd_store_ceph_conf = /etc/ceph/ceph.conf + rbd_store_chunk_size = 8 + +For more information about the configuration options available in Glance please refer to the OpenStack Configuration Reference: http://docs.openstack.org/. + +Enable copy-on-write cloning of images +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Note that this exposes the back end location via Glance's API, so the endpoint +with this option enabled should not be publicly accessible. + +Any OpenStack version except Mitaka +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +If you want to enable copy-on-write cloning of images, also add under the ``[DEFAULT]`` section:: + + show_image_direct_url = True + +Disable cache management (any OpenStack version) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Disable the Glance cache management to avoid images getting cached under ``/var/lib/glance/image-cache/``, +assuming your configuration file has ``flavor = keystone+cachemanagement``:: + + [paste_deploy] + flavor = keystone + +Image properties +~~~~~~~~~~~~~~~~ + +We recommend to use the following properties for your images: + +- ``hw_scsi_model=virtio-scsi``: add the virtio-scsi controller and get better performance and support for discard operation +- ``hw_disk_bus=scsi``: connect every cinder block devices to that controller +- ``hw_qemu_guest_agent=yes``: enable the QEMU guest agent +- ``os_require_quiesce=yes``: send fs-freeze/thaw calls through the QEMU guest agent + + +Configuring Cinder +------------------ + +OpenStack requires a driver to interact with Ceph block devices. You must also +specify the pool name for the block device. On your OpenStack node, edit +``/etc/cinder/cinder.conf`` by adding:: + + [DEFAULT] + ... + enabled_backends = ceph + glance_api_version = 2 + ... + [ceph] + volume_driver = cinder.volume.drivers.rbd.RBDDriver + volume_backend_name = ceph + rbd_pool = volumes + rbd_ceph_conf = /etc/ceph/ceph.conf + rbd_flatten_volume_from_snapshot = false + rbd_max_clone_depth = 5 + rbd_store_chunk_size = 4 + rados_connect_timeout = -1 + +If you are using `cephx authentication`_, also configure the user and uuid of +the secret you added to ``libvirt`` as documented earlier:: + + [ceph] + ... + rbd_user = cinder + rbd_secret_uuid = 457eb676-33da-42ec-9a8c-9293d545c337 + +Note that if you are configuring multiple cinder back ends, +``glance_api_version = 2`` must be in the ``[DEFAULT]`` section. + + +Configuring Cinder Backup +------------------------- + +OpenStack Cinder Backup requires a specific daemon so don't forget to install it. +On your Cinder Backup node, edit ``/etc/cinder/cinder.conf`` and add:: + + backup_driver = cinder.backup.drivers.ceph + backup_ceph_conf = /etc/ceph/ceph.conf + backup_ceph_user = cinder-backup + backup_ceph_chunk_size = 134217728 + backup_ceph_pool = backups + backup_ceph_stripe_unit = 0 + backup_ceph_stripe_count = 0 + restore_discard_excess_bytes = true + + +Configuring Nova to attach Ceph RBD block device +------------------------------------------------ + +In order to attach Cinder devices (either normal block or by issuing a boot +from volume), you must tell Nova (and libvirt) which user and UUID to refer to +when attaching the device. libvirt will refer to this user when connecting and +authenticating with the Ceph cluster. :: + + [libvirt] + ... + rbd_user = cinder + rbd_secret_uuid = 457eb676-33da-42ec-9a8c-9293d545c337 + +These two flags are also used by the Nova ephemeral back end. + + +Configuring Nova +---------------- + +In order to boot virtual machines directly from Ceph volumes, you must +configure the ephemeral backend for Nova. + +It is recommended to enable the RBD cache in your Ceph configuration file; this +has been enabled by default since the Giant release. Moreover, enabling the +client admin socket allows the collection of metrics and can be invaluable +for troubleshooting. + +This socket can be accessed on the hypvervisor (Nova compute) node:: + + ceph daemon /var/run/ceph/ceph-client.cinder.19195.32310016.asok help + +To enable RBD cache and admin sockets, ensure that on each hypervisor's +``ceph.conf`` contains:: + + [client] + rbd cache = true + rbd cache writethrough until flush = true + admin socket = /var/run/ceph/guests/$cluster-$type.$id.$pid.$cctid.asok + log file = /var/log/qemu/qemu-guest-$pid.log + rbd concurrent management ops = 20 + +Configure permissions for these directories:: + + mkdir -p /var/run/ceph/guests/ /var/log/qemu/ + chown qemu:libvirtd /var/run/ceph/guests /var/log/qemu/ + +Note that user ``qemu`` and group ``libvirtd`` can vary depending on your system. +The provided example works for RedHat based systems. + +.. tip:: If your virtual machine is already running you can simply restart it to enable the admin socket + + +Restart OpenStack +================= + +To activate the Ceph block device driver and load the block device pool name +into the configuration, you must restart the related OpenStack services. +For Debian based systems execute these commands on the appropriate nodes:: + + sudo glance-control api restart + sudo service nova-compute restart + sudo service cinder-volume restart + sudo service cinder-backup restart + +For Red Hat based systems execute:: + + sudo service openstack-glance-api restart + sudo service openstack-nova-compute restart + sudo service openstack-cinder-volume restart + sudo service openstack-cinder-backup restart + +Once OpenStack is up and running, you should be able to create a volume +and boot from it. + + +Booting from a Block Device +=========================== + +You can create a volume from an image using the Cinder command line tool:: + + cinder create --image-id {id of image} --display-name {name of volume} {size of volume} + +You can use `qemu-img`_ to convert from one format to another. For example:: + + qemu-img convert -f {source-format} -O {output-format} {source-filename} {output-filename} + qemu-img convert -f qcow2 -O raw precise-cloudimg.img precise-cloudimg.raw + +When Glance and Cinder are both using Ceph block devices, the image is a +copy-on-write clone, so new volumes are created quickly. In the OpenStack +dashboard, you can boot from that volume by performing the following steps: + +#. Launch a new instance. +#. Choose the image associated to the copy-on-write clone. +#. Select 'boot from volume'. +#. Select the volume you created. + +.. _qemu-img: ../qemu-rbd/#running-qemu-with-rbd diff --git a/doc/rbd/rbd-operations.rst b/doc/rbd/rbd-operations.rst new file mode 100644 index 000000000..cc27b5103 --- /dev/null +++ b/doc/rbd/rbd-operations.rst @@ -0,0 +1,16 @@ +============================== + Ceph Block Device Operations +============================== + +.. toctree:: + :maxdepth: 1 + + Snapshots<rbd-snapshot> + Exclusive Locking <rbd-exclusive-locks> + Mirroring <rbd-mirroring> + Live-Migration <rbd-live-migration> + Persistent Read-only Cache <rbd-persistent-read-only-cache> + Persistent Write-back Cache <rbd-persistent-write-back-cache> + Encryption <rbd-encryption> + Config Settings (librbd) <rbd-config-ref/> + RBD Replay <rbd-replay> diff --git a/doc/rbd/rbd-persistent-read-only-cache.rst b/doc/rbd/rbd-persistent-read-only-cache.rst new file mode 100644 index 000000000..5bef7f592 --- /dev/null +++ b/doc/rbd/rbd-persistent-read-only-cache.rst @@ -0,0 +1,201 @@ +=============================== + RBD Persistent Read-only Cache +=============================== + +.. index:: Ceph Block Device; Persistent Read-only Cache + +Shared, Read-only Parent Image Cache +==================================== + +`Cloned RBD images`_ usually modify only a small fraction of the parent +image. For example, in a VDI use-case, VMs are cloned from the same +base image and initially differ only by hostname and IP address. During +booting, all of these VMs read portions of the same parent +image data. If we have a local cache of the parent +image, this speeds up reads on the caching host. We also achieve +reduction of client-to-cluster network traffic. +RBD cache must be explicitly enabled in +``ceph.conf``. The ``ceph-immutable-object-cache`` daemon is responsible for +caching the parent content on the local disk, and future reads on that data +will be serviced from the local cache. + +.. note:: RBD shared read-only parent image cache requires the Ceph Nautilus release or later. + +.. ditaa:: + + +--------------------------------------------------------+ + | QEMU | + +--------------------------------------------------------+ + | librbd (cloned images) | + +-------------------+-+----------------------------------+ + | librados | | ceph--immutable--object--cache | + +-------------------+ +----------------------------------+ + | OSDs/Mons | | local cached parent image | + +-------------------+ +----------------------------------+ + + +Enable RBD Shared Read-only Parent Image Cache +---------------------------------------------- + +To enable RBD shared read-only parent image cache, the following Ceph settings +need to added in the ``[client]`` `section`_ of your ``ceph.conf`` file:: + + rbd parent cache enabled = true + rbd plugins = parent_cache + +Immutable Object Cache Daemon +============================= + +Introduction and Generic Settings +--------------------------------- + +The ``ceph-immutable-object-cache`` daemon is responsible for caching parent +image content within its local caching directory. Using SSDs as the underlying +storage is recommended because doing so provides better performance. + +The key components of the daemon are: + +#. **Domain socket based IPC:** The daemon listens on a local domain socket at + startup and waits for connections from librbd clients. + +#. **LRU based promotion/demotion policy:** The daemon maintains in-memory + statistics of cache hits for each cache file. It demotes the cold cache + if capacity reaches the configured threshold. + +#. **File-based caching store:** The daemon maintains a simple file-based cache + store. On promotion, the RADOS objects are fetched from RADOS cluster and + stored in the local caching directory. + +When each cloned RBD image is opened, ``librbd`` tries to connect to the cache +daemon through its Unix domain socket. After ``librbd`` is successfully +connected, it coordinates with the daemon upon every subsequent read. In the +case of an uncached read, the daemon promotes the RADOS object to the local +caching directory and the next read of the object is serviced from the cache. +The daemon maintains simple LRU statistics, which are used to evict cold cache +files when required (for example, when the cache is at capacity and under +pressure). + +Here are some important cache configuration settings: + +``immutable_object_cache_sock`` + +:Description: The path to the domain socket used for communication between + librbd clients and the ceph-immutable-object-cache daemon. +:Type: String +:Required: No +:Default: ``/var/run/ceph/immutable_object_cache_sock`` + + +``immutable_object_cache_path`` + +:Description: The immutable object cache data directory. +:Type: String +:Required: No +:Default: ``/tmp/ceph_immutable_object_cache`` + + +``immutable_object_cache_max_size`` + +:Description: The max size for immutable cache. +:Type: Size +:Required: No +:Default: ``1G`` + + +``immutable_object_cache_watermark`` + +:Description: The high-water mark for the cache. The value is between (0, 1). + If the cache size reaches this threshold the daemon will start + to delete cold cache based on LRU statistics. +:Type: Float +:Required: No +:Default: ``0.9`` + +The ``ceph-immutable-object-cache`` daemon is available within the optional +``ceph-immutable-object-cache`` distribution package. + +.. important:: ``ceph-immutable-object-cache`` daemon requires the ability to + connect RADOS clusters. + +Running the Immutable Object Cache Daemon +----------------------------------------- + +``ceph-immutable-object-cache`` daemon should use a unique Ceph user ID. +To `create a Ceph user`_, with ``ceph`` specify the ``auth get-or-create`` +command, user name, monitor caps, and OSD caps:: + + ceph auth get-or-create client.ceph-immutable-object-cache.{unique id} mon 'allow r' osd 'profile rbd-read-only' + +The ``ceph-immutable-object-cache`` daemon can be managed by ``systemd`` by specifying the user +ID as the daemon instance:: + + systemctl enable ceph-immutable-object-cache@ceph-immutable-object-cache.{unique id} + +The ``ceph-immutable-object-cache`` can also be run in foreground by ``ceph-immutable-object-cache`` command:: + + ceph-immutable-object-cache -f --log-file={log_path} + +QOS Settings +------------ + +The immutable object cache supports throttling, controlled by the following settings: + +``immutable_object_cache_qos_schedule_tick_min`` + +:Description: Minimum schedule tick for immutable object cache. +:Type: Milliseconds +:Required: No +:Default: ``50`` + + +``immutable_object_cache_qos_iops_limit`` + +:Description: The desired immutable object cache IO operations limit per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``immutable_object_cache_qos_iops_burst`` + +:Description: The desired burst limit of immutable object cache IO operations. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``immutable_object_cache_qos_iops_burst_seconds`` + +:Description: The desired burst duration in seconds of immutable object cache IO operations. +:Type: Seconds +:Required: No +:Default: ``1`` + + +``immutable_object_cache_qos_bps_limit`` + +:Description: The desired immutable object cache IO bytes limit per second. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``immutable_object_cache_qos_bps_burst`` + +:Description: The desired burst limit of immutable object cache IO bytes. +:Type: Unsigned Integer +:Required: No +:Default: ``0`` + + +``immutable_object_cache_qos_bps_burst_seconds`` + +:Description: The desired burst duration in seconds of immutable object cache IO bytes. +:Type: Seconds +:Required: No +:Default: ``1`` + +.. _Cloned RBD Images: ../rbd-snapshot/#layering +.. _section: ../../rados/configuration/ceph-conf/#configuration-sections +.. _create a Ceph user: ../../rados/operations/user-management#add-a-user + diff --git a/doc/rbd/rbd-persistent-write-back-cache.rst b/doc/rbd/rbd-persistent-write-back-cache.rst new file mode 100644 index 000000000..8066014e9 --- /dev/null +++ b/doc/rbd/rbd-persistent-write-back-cache.rst @@ -0,0 +1,133 @@ +================================ + RBD Persistent Write-back Cache +================================ + +.. index:: Ceph Block Device; Persistent Write-back Cache + +Persistent Write-back Cache +=========================== + +The persistent write-back cache provides a persistent, fault-tolerant write-back +cache for librbd-based RBD clients. + +This cache uses a log-ordered write-back design which maintains checkpoints +internally so that writes that get flushed back to the cluster are always +crash consistent. Even if the client cache is lost entirely, the disk image is +still consistent but the data will appear to be stale. + +This cache can be used with PMEM or SSD as a cache device. + +Usage +===== + +The persistent write-back cache manages the cache data in a persistent device. +It looks for and creates cache files in a configured directory, and then caches +data in the file. + +The persistent write-back cache can't be enabled without the exclusive-lock +feature. It tries to enable the write-back cache only when the exclusive lock +is acquired. + +The cache provides two different persistence modes. In persistent-on-write mode, +the writes are completed only when they are persisted to the cache device and +will be readable after a crash. In persistent-on-flush mode, the writes are +completed as soon as it no longer needs the caller's data buffer to complete +the writes, but does not guarantee that writes will be readable after a crash. +The data is persisted to the cache device when a flush request is received. + +Initially it defaults to the persistent-on-write mode and it switches to +persistent-on-flush mode after the first flush request is received. + +Enable Persistent Write-back Cache +======================================== + +To enable the persistent write-back cache, the following Ceph settings +need to be enabled.:: + + rbd persistent cache mode = {cache-mode} + rbd plugins = pwl_cache + +Value of {cache-mode} can be ``rwl``, ``ssd`` or ``disabled``. By default the +cache is disabled. + +Here are some cache configuration settings: + +- ``rbd_persistent_cache_path`` A file folder to cache data. This folder must + have DAX enabled (see `DAX`_) when using ``rwl`` mode to avoid performance + degradation. + +- ``rbd_persistent_cache_size`` The cache size per image. The minimum cache + size is 1 GB. + +The above configurations can be set per-host, per-pool, per-image etc. Eg, to +set per-host, add the overrides to the appropriate `section`_ in the host's +``ceph.conf`` file. To set per-pool, per-image, etc, please refer to the +``rbd config`` `commands`_. + +Cache Status +------------ + +The persistent write-back cache is enabled when the exclusive lock is acquired, +and it is closed when the exclusive lock is released. To check the cache status, +users may use the command ``rbd status``. :: + + rbd status {pool-name}/{image-name} + +The status of the cache is shown, including present, clean, cache size and the +location as well as some basic metrics. + +For example:: + + $ rbd status rbd/foo + Watchers: + watcher=10.10.0.102:0/1061883624 client.25496 cookie=140338056493088 + Persistent cache state: + host: sceph9 + path: /mnt/nvme0/rbd-pwl.rbd.101e5824ad9a.pool + size: 1 GiB + mode: ssd + stats_timestamp: Sun Apr 10 13:26:32 2022 + present: true empty: false clean: false + allocated: 509 MiB + cached: 501 MiB + dirty: 338 MiB + free: 515 MiB + hits_full: 1450 / 61% + hits_partial: 0 / 0% + misses: 924 + hit_bytes: 192 MiB / 66% + miss_bytes: 97 MiB + +Flush Cache +----------- + +To flush a cache file with ``rbd``, specify the ``persistent-cache flush`` +command, the pool name and the image name. :: + + rbd persistent-cache flush {pool-name}/{image-name} + +If the application dies unexpectedly, this command can also be used to flush +the cache back to OSDs. + +For example:: + + $ rbd persistent-cache flush rbd/foo + +Invalidate Cache +---------------- + +To invalidate (discard) a cache file with ``rbd``, specify the +``persistent-cache invalidate`` command, the pool name and the image name. :: + + rbd persistent-cache invalidate {pool-name}/{image-name} + +The command removes the cache metadata of the corresponding image, disables +the cache feature and deletes the local cache file if it exists. + +For example:: + + $ rbd persistent-cache invalidate rbd/foo + +.. _section: ../../rados/configuration/ceph-conf/#configuration-sections +.. _commands: ../../man/8/rbd#commands +.. _DAX: https://www.kernel.org/doc/Documentation/filesystems/dax.txt diff --git a/doc/rbd/rbd-replay.rst b/doc/rbd/rbd-replay.rst new file mode 100644 index 000000000..b1fc4973f --- /dev/null +++ b/doc/rbd/rbd-replay.rst @@ -0,0 +1,42 @@ +=================== + RBD Replay +=================== + +.. index:: Ceph Block Device; RBD Replay + +RBD Replay is a set of tools for capturing and replaying RADOS Block Device +(RBD) workloads. To capture an RBD workload, ``lttng-tools`` must be installed +on the client, and ``librbd`` on the client must be the v0.87 (Giant) release +or later. To replay an RBD workload, ``librbd`` on the client must be the Giant +release or later. + +Capture and replay takes three steps: + +#. Capture the trace. Make sure to capture ``pthread_id`` context:: + + mkdir -p traces + lttng create -o traces librbd + lttng enable-event -u 'librbd:*' + lttng add-context -u -t pthread_id + lttng start + # run RBD workload here + lttng stop + +#. Process the trace with `rbd-replay-prep`_:: + + rbd-replay-prep traces/ust/uid/*/* replay.bin + +#. Replay the trace with `rbd-replay`_. Use read-only until you know + it's doing what you want:: + + rbd-replay --read-only replay.bin + +.. important:: ``rbd-replay`` will destroy data by default. Do not use against + an image you wish to keep, unless you use the ``--read-only`` option. + +The replayed workload does not have to be against the same RBD image or even the +same cluster as the captured workload. To account for differences, you may need +to use the ``--pool`` and ``--map-image`` options of ``rbd-replay``. + +.. _rbd-replay: ../../man/8/rbd-replay +.. _rbd-replay-prep: ../../man/8/rbd-replay-prep diff --git a/doc/rbd/rbd-snapshot.rst b/doc/rbd/rbd-snapshot.rst new file mode 100644 index 000000000..765a1555b --- /dev/null +++ b/doc/rbd/rbd-snapshot.rst @@ -0,0 +1,367 @@ +=========== + Snapshots +=========== + +.. index:: Ceph Block Device; snapshots + +A snapshot is a read-only logical copy of an image at a particular point in +time: a checkpoint. One of the advanced features of Ceph block devices is that +you can create snapshots of images to retain point-in-time state history. Ceph +also supports snapshot layering, which allows you to clone images (for example, +VM images) quickly and easily. Ceph block device snapshots are managed using +the ``rbd`` command and several higher-level interfaces, including `QEMU`_, +`libvirt`_, `OpenStack`_, and `CloudStack`_. + +.. important:: To use RBD snapshots, you must have a running Ceph cluster. + +.. note:: Because RBD is unaware of any file system within an image (volume), + snapshots are merely `crash-consistent` unless they are coordinated within + the mounting (attaching) operating system. We therefore recommend that you + pause or stop I/O before taking a snapshot. + + If the volume contains a file system, the file system should be in an + internally consistent state before a snapshot is taken. Snapshots taken + without write quiescing could need an `fsck` pass before they are mounted + again. To quiesce I/O you can use `fsfreeze` command. See the `fsfreeze(8)` + man page for more details. + + For virtual machines, `qemu-guest-agent` can be used to automatically freeze + file systems when creating a snapshot. + +.. ditaa:: + + +------------+ +-------------+ + | {s} | | {s} c999 | + | Active |<-------*| Snapshot | + | Image | | of Image | + | (stop i/o) | | (read only) | + +------------+ +-------------+ + + +Cephx Notes +=========== + +When `cephx`_ authentication is enabled (it is by default), you must specify a +user name or ID and a path to the keyring containing the corresponding key. See +:ref:`User Management <user-management>` for details. + +.. prompt:: bash $ + + rbd --id {user-ID} --keyring /path/to/secret [commands] + rbd --name {username} --keyring /path/to/secret [commands] + +For example: + +.. prompt:: bash $ + + rbd --id admin --keyring /etc/ceph/ceph.keyring [commands] + rbd --name client.admin --keyring /etc/ceph/ceph.keyring [commands] + +.. tip:: Add the user and secret to the ``CEPH_ARGS`` environment variable to + avoid re-entry of these parameters. + + +Snapshot Basics +=============== + +The following procedures demonstrate how to create, list, and remove +snapshots using the ``rbd`` command. + +Create Snapshot +--------------- + +To create a snapshot, use the ``rbd snap create`` command and specify the pool +name, the image name, and the snap name: + +.. prompt:: bash $ + + rbd snap create {pool-name}/{image-name}@{snap-name} + +For example: + +.. prompt:: bash $ + + rbd snap create rbd/foo@snapname + + +List Snapshots +-------------- + +To list the snapshots of an image, use the ``rbd snap ls`` command and specify +the pool name and the image name: + +.. prompt:: bash $ + + rbd snap ls {pool-name}/{image-name} + +For example: + +.. prompt:: bash $ + + rbd snap ls rbd/foo + + +Roll back Snapshot +------------------ + +To roll back to a snapshot, use the ``rbd snap rollback`` command and specify +the pool name, the image name, and the snap name: + +.. prompt:: bash $ + + rbd snap rollback {pool-name}/{image-name}@{snap-name} + +For example: + +.. prompt:: bash $ + + rbd snap rollback rbd/foo@snapname + + +.. note:: Rolling back an image to a snapshot means overwriting the current + version of the image with data from a snapshot. The time it takes to execute + a rollback increases with the size of the image. It is **faster to clone** + from a snapshot **than to roll back** an image to a snapshot. Cloning from a + snapshot is the preferred method of returning to a pre-existing state. + + +Delete a Snapshot +----------------- + +To delete a snapshot, use the ``rbd snap rm`` command and specify the pool +name, the image name, and the snap name: + +.. prompt:: bash $ + + rbd snap rm {pool-name}/{image-name}@{snap-name} + +For example: + +.. prompt:: bash $ + + rbd snap rm rbd/foo@snapname + + +.. note:: Ceph OSDs delete data asynchronously, so deleting a snapshot does + not immediately free up the capacity of the underlying OSDs. This process is + known as "snaptrim", and is referred to as such in ``ceph status`` output. + +Purge Snapshots +--------------- + +To delete all snapshots, use the ``rbd snap purge`` command and specify the +pool name and the image name: + +.. prompt:: bash $ + + rbd snap purge {pool-name}/{image-name} + +For example: + +.. prompt:: bash $ + + rbd snap purge rbd/foo + + +.. index:: Ceph Block Device; snapshot layering + +Layering +======== + +Ceph supports the ability to create many copy-on-write (COW) clones of a block +device snapshot. Snapshot layering enables Ceph block device clients to create +images very quickly. For example, you might create a block device image with a +Linux VM written to it, snapshot the image, protect the snapshot, and create as +many copy-on-write clones as you like. A snapshot is read-only, so cloning a +snapshot simplifies semantics, making it possible to create clones rapidly. + + +.. ditaa:: + + +-------------+ +-------------+ + | {s} c999 | | {s} | + | Snapshot | Child refers | COW Clone | + | of Image |<------------*| of Snapshot | + | | to Parent | | + | (read only) | | (writable) | + +-------------+ +-------------+ + + Parent Child + +.. note:: The terms "parent" and "child" refer to a Ceph block device snapshot + (parent) and the corresponding image cloned from the snapshot (child). + These terms are important for the command line usage below. + +Each cloned image (child) stores a reference to its parent image, which enables +the cloned image to open the parent snapshot and read it. + +A copy-on-write clone of a snapshot behaves exactly like any other Ceph +block device image. You can read to, write from, clone, and resize cloned +images. There are no special restrictions with cloned images. However, the +copy-on-write clone of a snapshot depends on the snapshot, so you must +protect the snapshot before you clone it. The diagram below depicts this +process. + +.. note:: Ceph supports the cloning of only "RBD format 2" images (that is, + images created without specifying ``--image-format 1``). The Linux kernel + client supports cloned images beginning with the 3.10 release. + +Getting Started with Layering +----------------------------- + +Ceph block device layering is a simple process. You must have an image. You +must create a snapshot of the image. You must protect the snapshot. After you +have performed these steps, you can begin cloning the snapshot. + +.. ditaa:: + + +----------------------------+ +-----------------------------+ + | | | | + | Create Block Device Image |------->| Create a Snapshot | + | | | | + +----------------------------+ +-----------------------------+ + | + +--------------------------------------+ + | + v + +----------------------------+ +-----------------------------+ + | | | | + | Protect the Snapshot |------->| Clone the Snapshot | + | | | | + +----------------------------+ +-----------------------------+ + + +The cloned image has a reference to the parent snapshot, and includes the pool +ID, the image ID, and the snapshot ID. The inclusion of the pool ID means that +you may clone snapshots from one pool to images in another pool. + +#. **Image Template:** A common use case for block device layering is to create + a base image and a snapshot that serves as a template for clones. For + example: a user may create an image for a Linux distribution (for example, + Ubuntu 22.04) and create a snapshot of it. The user may occasionally update + the image and create a new snapshot (by using such commands as ``sudo + apt-get update``, ``sudo apt-get upgrade``, or ``sudo apt-get dist-upgrade`` + followed by ``rbd snap create``). As the image matures, the user can clone + any one of the snapshots. + +#. **Extended Template:** A more advanced use case includes extending a + template image to provide more information than a base image. For + example, a user may clone an image (for example, a VM template) and install + other software (for example, a database, a content management system, an + analytics system) and then snapshot the extended image, which may itself be + updated just like the base image. + +#. **Template Pool:** One way to use block device layering is to create a pool + that contains (1) base images that act as templates and (2) snapshots of + those templates. You may then extend read-only privileges to users so that + they may clone the snapshots even though they do not have permissions that + allow them to write or execute within the pool. + +#. **Image Migration/Recovery:** One way to use block device layering is to + migrate or recover data from one pool into another pool. + +Protecting a Snapshot +--------------------- + +Clones access the parent snapshots. All clones would break if a user +inadvertently deleted the parent snapshot. To prevent data loss, you must +protect the snapshot before you can clone it: + +.. prompt:: bash $ + + rbd snap protect {pool-name}/{image-name}@{snapshot-name} + +For example: + +.. prompt:: bash $ + + rbd snap protect rbd/foo@snapname + +.. note:: You cannot delete a protected snapshot. + +Cloning a Snapshot +------------------ + +To clone a snapshot, specify the parent pool, the parent image, and the parent +snapshot; and also the child pool together with the image name. You must +protect the snapshot before you can clone it: + +.. prompt:: bash $ + + rbd clone {pool-name}/{parent-image-name}@{snap-name} {pool-name}/{child-image-name} + +For example: + +.. prompt:: bash $ + + rbd clone rbd/foo@snapname rbd/bar + + +.. note:: You may clone a snapshot from one pool to an image in another pool. + For example, you may maintain read-only images and snapshots as templates in + one pool, and writeable clones in another pool. + +Unprotecting a Snapshot +----------------------- + +Before you can delete a snapshot, you must first unprotect it. Additionally, +you may *NOT* delete snapshots that have references from clones. You must +flatten or delete each clone of a snapshot before you can unprotect the +snapshot: + +.. prompt:: bash $ + + rbd snap unprotect {pool-name}/{image-name}@{snapshot-name} + +For example: + +.. prompt:: bash $ + + rbd snap unprotect rbd/foo@snapname + + +Listing Children of a Snapshot +------------------------------ + +To list the children of a snapshot, use the ``rbd children`` command and +specify the pool name, the image name, and the snap name: + +.. prompt:: bash $ + + rbd children {pool-name}/{image-name}@{snapshot-name} + +For example: + +.. prompt:: bash $ + + rbd children rbd/foo@snapname + + +Flattening a Cloned Image +------------------------- + +Cloned images retain a reference to the parent snapshot. When you remove the +reference to the parent snapshot from the clone, you effectively "flatten" the +clone by copying the data stored in the snapshot to the clone. The time it +takes to flatten a clone increases with the size of the snapshot. To delete a +snapshot, you must first flatten the child images (or delete them): + +.. prompt:: bash $ + + rbd flatten {pool-name}/{image-name} + +For example: + +.. prompt:: bash $ + + rbd flatten rbd/bar + +.. note:: Since a flattened image contains all the data stored in the snapshot, + a flattened image takes up more storage space than a layered clone does. + + +.. _cephx: ../../rados/configuration/auth-config-ref/ +.. _QEMU: ../qemu-rbd/ +.. _OpenStack: ../rbd-openstack/ +.. _CloudStack: ../rbd-cloudstack/ +.. _libvirt: ../libvirt/ diff --git a/doc/rbd/rbd-windows.rst b/doc/rbd/rbd-windows.rst new file mode 100644 index 000000000..271e85592 --- /dev/null +++ b/doc/rbd/rbd-windows.rst @@ -0,0 +1,158 @@ +============== +RBD on Windows +============== + +The ``rbd`` command can be used to create, remove, import, export, map or +unmap images exactly like it would on Linux. Make sure to check the +`RBD basic commands`_ guide. + +``librbd.dll`` is also available for applications that can natively use Ceph. + +Please check the `installation guide`_ to get started. + +Windows service +=============== +On Windows, ``rbd-wnbd`` daemons are managed by a centralized service. This allows +decoupling the daemons from the Windows session from which they originate. At +the same time, the service is responsible of recreating persistent mappings, +usually when the host boots. + +Note that only one such service may run per host. + +By default, all image mappings are persistent. Non-persistent mappings can be +requested using the ``-onon-persistent`` ``rbd`` flag. + +Persistent mappings are recreated when the service starts, unless explicitly +unmapped. The service disconnects the mappings when being stopped. This also +allows adjusting the Windows service start order so that RBD images can be +mapped before starting services that may depend on it, such as VMMS. + +In order to be able to reconnect the images, ``rbd-wnbd`` stores mapping +information in the Windows registry at the following location: +``SYSTEM\CurrentControlSet\Services\rbd-wnbd``. + +The following command can be used to configure the service. Please update +the ``rbd-wnbd.exe`` path accordingly:: + + New-Service -Name "ceph-rbd" ` + -Description "Ceph RBD Mapping Service" ` + -BinaryPathName "c:\ceph\rbd-wnbd.exe service" ` + -StartupType Automatic + +Note that the Ceph MSI installer takes care of creating the ``ceph-rbd`` +Windows service. + +Usage +===== + +Integration +----------- + +RBD images can be exposed to the OS and host Windows partitions or they can be +attached to Hyper-V VMs in the same way as iSCSI disks. + +Starting with Openstack Wallaby, the Nova Hyper-V driver can attach RBD Cinder +volumes to Hyper-V VMs. + +Mapping images +-------------- + +The workflow and CLI is similar to the Linux counterpart, with a few +notable differences: + +* device paths cannot be requested. The disk number and path will be picked by + Windows. If a device path is provided by the used when mapping an image, it + will be used as an identifier, which can also be used when unmapping the + image. +* the ``show`` command was added, which describes a specific mapping. + This can be used for retrieving the disk path. +* the ``service`` command was added, allowing ``rbd-wnbd`` to run as a Windows service. + All mappings are by default perisistent, being recreated when the service + stops, unless explicitly unmapped. The service disconnects the mappings + when being stopped. +* the ``list`` command also includes a ``status`` column. + +The purpose of the ``service`` mode is to ensure that mappings survive reboots +and that the Windows service start order can be adjusted so that RBD images can +be mapped before starting services that may depend on it, such as VMMS. + +The mapped images can either be consumed by the host directly or exposed to +Hyper-V VMs. + +Hyper-V VM disks +---------------- + +The following sample imports an RBD image and boots a Hyper-V VM using it:: + + # Feel free to use any other image. This one is convenient to use for + # testing purposes because it's very small (~15MB) and the login prompt + # prints the pre-configured password. + wget http://download.cirros-cloud.net/0.5.1/cirros-0.5.1-x86_64-disk.img ` + -OutFile cirros-0.5.1-x86_64-disk.img + + # We'll need to make sure that the imported images are raw (so no qcow2 or vhdx). + # You may get qemu-img from https://cloudbase.it/qemu-img-windows/ + # You can add the extracted location to $env:Path or update the path accordingly. + qemu-img convert -O raw cirros-0.5.1-x86_64-disk.img cirros-0.5.1-x86_64-disk.raw + + rbd import cirros-0.5.1-x86_64-disk.raw + # Let's give it a hefty 100MB size. + rbd resize cirros-0.5.1-x86_64-disk.raw --size=100MB + + rbd device map cirros-0.5.1-x86_64-disk.raw + + # Let's have a look at the mappings. + rbd device list + Get-Disk + + $mappingJson = rbd-wnbd show cirros-0.5.1-x86_64-disk.raw --format=json + $mappingJson = $mappingJson | ConvertFrom-Json + + $diskNumber = $mappingJson.disk_number + + New-VM -VMName BootFromRBD -MemoryStartupBytes 512MB + # The disk must be turned offline before it can be passed to Hyper-V VMs + Set-Disk -Number $diskNumber -IsOffline $true + Add-VMHardDiskDrive -VMName BootFromRBD -DiskNumber $diskNumber + Start-VM -VMName BootFromRBD + +Windows partitions +------------------ + +The following sample creates an empty RBD image, attaches it to the host and +initializes a partition:: + + rbd create blank_image --size=1G + rbd device map blank_image -onon-persistent + + $mappingJson = rbd-wnbd show blank_image --format=json + $mappingJson = $mappingJson | ConvertFrom-Json + + $diskNumber = $mappingJson.disk_number + + # The disk must be online before creating or accessing partitions. + Set-Disk -Number $diskNumber -IsOffline $false + + # Initialize the disk, partition it and create a fileystem. + Get-Disk -Number $diskNumber | ` + Initialize-Disk -PassThru | ` + New-Partition -AssignDriveLetter -UseMaximumSize | ` + Format-Volume -Force -Confirm:$false + +Limitations +----------- + +At the moment, the Microsoft Failover Cluster can't use WNBD disks as +Cluster Shared Volumes (CSVs) underlying storage. The main reason is that +``WNBD`` and ``rbd-wnbd`` don't support the *SCSI Persistent Reservations* +feature yet. + +Troubleshooting +=============== + +Please consult the `Windows troubleshooting`_ page. + +.. _Windows troubleshooting: ../../install/windows-troubleshooting +.. _installation guide: ../../install/windows-install +.. _RBD basic commands: ../rados-rbd-cmds +.. _WNBD driver: https://github.com/cloudbase/wnbd |