================================== Pool Placement and Storage Classes ================================== .. contents:: Placement Targets ================= .. versionadded:: Jewel Placement targets control which `Pools`_ are associated with a particular bucket. A bucket's placement target is selected on creation, and cannot be modified. The ``radosgw-admin bucket stats`` command will display its ``placement_rule``. The zonegroup configuration contains a list of placement targets with an initial target named ``default-placement``. The zone configuration then maps each zonegroup placement target name onto its local storage. This zone placement information includes the ``index_pool`` name for the bucket index, the ``data_extra_pool`` name for metadata about incomplete multipart uploads, and a ``data_pool`` name for each storage class. .. _storage_classes: Storage Classes =============== .. versionadded:: Nautilus Storage classes are used to customize the placement of object data. S3 Bucket Lifecycle rules can automate the transition of objects between storage classes. Storage classes are defined in terms of placement targets. Each zonegroup placement target lists its available storage classes with an initial class named ``STANDARD``. The zone configuration is responsible for providing a ``data_pool`` pool name for each of the zonegroup's storage classes. Zonegroup/Zone Configuration ============================ Placement configuration is performed with ``radosgw-admin`` commands on the zonegroups and zones. The zonegroup placement configuration can be queried with: :: $ radosgw-admin zonegroup get { "id": "ab01123f-e0df-4f29-9d71-b44888d67cd5", "name": "default", "api_name": "default", ... "placement_targets": [ { "name": "default-placement", "tags": [], "storage_classes": [ "STANDARD" ] } ], "default_placement": "default-placement", ... } The zone placement configuration can be queried with: :: $ radosgw-admin zone get { "id": "557cdcee-3aae-4e9e-85c7-2f86f5eddb1f", "name": "default", "domain_root": "default.rgw.meta:root", ... "placement_pools": [ { "key": "default-placement", "val": { "index_pool": "default.rgw.buckets.index", "storage_classes": { "STANDARD": { "data_pool": "default.rgw.buckets.data" } }, "data_extra_pool": "default.rgw.buckets.non-ec", "index_type": 0, "inline_data": true } } ], ... } .. note:: If you have not done any previous `Multisite Configuration`_, a ``default`` zone and zonegroup are created for you, and changes to the zone/zonegroup will not take effect until the Ceph Object Gateways are restarted. If you have created a realm for multisite, the zone/zonegroup changes will take effect once the changes are committed with ``radosgw-admin period update --commit``. Adding a Placement Target ------------------------- To create a new placement target named ``temporary``, start by adding it to the zonegroup: :: $ radosgw-admin zonegroup placement add \ --rgw-zonegroup default \ --placement-id temporary Then provide the zone placement info for that target: :: $ radosgw-admin zone placement add \ --rgw-zone default \ --placement-id temporary \ --data-pool default.rgw.temporary.data \ --index-pool default.rgw.temporary.index \ --data-extra-pool default.rgw.temporary.non-ec .. note:: With default placement target settings, RGW stores an object's first data chunk in the RADOS "head" object along with xattr metadata. The `--placement-inline-data=false` flag may be passed with the `zone placement add` or `zone placement modify` commands to change this behavior for new objects stored on the target. When data is stored inline (default), it may provide an advantage for read/write workloads since the first chunk of an object's data can be retrieved/stored in a single librados call along with object metadata. On the other hand, a target that does not store data inline can provide a performance benefit for RGW client delete requests when the BlueStore DB is located on faster storage than bucket data since it eliminates the need to access slower devices synchronously while processing the client request. In that case, data associated with the deleted objects is removed asynchronously in the background by garbage collection. .. _adding_a_storage_class: Adding a Storage Class ---------------------- To add a new storage class named ``GLACIER`` to the ``default-placement`` target, start by adding it to the zonegroup: :: $ radosgw-admin zonegroup placement add \ --rgw-zonegroup default \ --placement-id default-placement \ --storage-class GLACIER Then provide the zone placement info for that storage class: :: $ radosgw-admin zone placement add \ --rgw-zone default \ --placement-id default-placement \ --storage-class GLACIER \ --data-pool default.rgw.glacier.data \ --compression lz4 Customizing Placement ===================== Default Placement ----------------- By default, new buckets will use the zonegroup's ``default_placement`` target. This zonegroup setting can be changed with: :: $ radosgw-admin zonegroup placement default \ --rgw-zonegroup default \ --placement-id new-placement User Placement -------------- A Ceph Object Gateway user can override the zonegroup's default placement target by setting a non-empty ``default_placement`` field in the user info. Similarly, the ``default_storage_class`` can override the ``STANDARD`` storage class applied to objects by default. :: $ radosgw-admin user info --uid testid { ... "default_placement": "", "default_storage_class": "", "placement_tags": [], ... } If a zonegroup's placement target contains any ``tags``, users will be unable to create buckets with that placement target unless their user info contains at least one matching tag in its ``placement_tags`` field. This can be useful to restrict access to certain types of storage. The ``radosgw-admin`` command can modify these fields directly with: :: $ radosgw-admin user modify \ --uid \ --placement-id \ --storage-class \ --tags .. _s3_bucket_placement: S3 Bucket Placement ------------------- When creating a bucket with the S3 protocol, a placement target can be provided as part of the LocationConstraint to override the default placement targets from the user and zonegroup. Normally, the LocationConstraint must match the zonegroup's ``api_name``: :: default A custom placement target can be added to the ``api_name`` following a colon: :: default:new-placement Swift Bucket Placement ---------------------- When creating a bucket with the Swift protocol, a placement target can be provided in the HTTP header ``X-Storage-Policy``: :: X-Storage-Policy: new-placement Using Storage Classes ===================== All placement targets have a ``STANDARD`` storage class which is applied to new objects by default. The user can override this default with its ``default_storage_class``. To create an object in a non-default storage class, provide that storage class name in an HTTP header with the request. The S3 protocol uses the ``X-Amz-Storage-Class`` header, while the Swift protocol uses the ``X-Object-Storage-Class`` header. When using AWS S3 SDKs such as ``boto3``, it is important that non-default storage class names match those provided by AWS S3, or else the SDK will drop the request and raise an exception. S3 Object Lifecycle Management can then be used to move object data between storage classes using ``Transition`` actions. .. _`Pools`: ../pools .. _`Multisite Configuration`: ../multisite