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diff --git a/doc/start/intro.rst b/doc/start/intro.rst new file mode 100644 index 000000000..3a50a8733 --- /dev/null +++ b/doc/start/intro.rst @@ -0,0 +1,99 @@ +=============== + Intro to Ceph +=============== + +Ceph can be used to provide :term:`Ceph Object Storage` to :term:`Cloud +Platforms` and Ceph can be used to provide :term:`Ceph Block Device` services +to :term:`Cloud Platforms`. Ceph can be used to deploy a :term:`Ceph File +System`. All :term:`Ceph Storage Cluster` deployments begin with setting up +each :term:`Ceph Node` and then setting up the network. + +A Ceph Storage Cluster requires the following: at least one Ceph Monitor and at +least one Ceph Manager, and at least as many Ceph OSDs as there are copies of +an object stored on the Ceph cluster (for example, if three copies of a given +object are stored on the Ceph cluster, then at least three OSDs must exist in +that Ceph cluster). + +The Ceph Metadata Server is necessary to run Ceph File System clients. + +.. note:: + + It is a best practice to have a Ceph Manager for each Monitor, but it is not + necessary. + +.. ditaa:: + + +---------------+ +------------+ +------------+ +---------------+ + | OSDs | | Monitors | | Managers | | MDSs | + +---------------+ +------------+ +------------+ +---------------+ + +- **Monitors**: A :term:`Ceph Monitor` (``ceph-mon``) maintains maps + of the cluster state, including the monitor map, manager map, the + OSD map, the MDS map, and the CRUSH map. These maps are critical + cluster state required for Ceph daemons to coordinate with each other. + Monitors are also responsible for managing authentication between + daemons and clients. At least three monitors are normally required + for redundancy and high availability. + +- **Managers**: A :term:`Ceph Manager` daemon (``ceph-mgr``) is + responsible for keeping track of runtime metrics and the current + state of the Ceph cluster, including storage utilization, current + performance metrics, and system load. The Ceph Manager daemons also + host python-based modules to manage and expose Ceph cluster + information, including a web-based :ref:`mgr-dashboard` and + `REST API`_. At least two managers are normally required for high + availability. + +- **Ceph OSDs**: An Object Storage Daemon (:term:`Ceph OSD`, + ``ceph-osd``) stores data, handles data replication, recovery, + rebalancing, and provides some monitoring information to Ceph + Monitors and Managers by checking other Ceph OSD Daemons for a + heartbeat. At least three Ceph OSDs are normally required for + redundancy and high availability. + +- **MDSs**: A :term:`Ceph Metadata Server` (MDS, ``ceph-mds``) stores + metadata on behalf of the :term:`Ceph File System` (i.e., Ceph Block + Devices and Ceph Object Storage do not use MDS). Ceph Metadata + Servers allow POSIX file system users to execute basic commands (like + ``ls``, ``find``, etc.) without placing an enormous burden on the + Ceph Storage Cluster. + +Ceph stores data as objects within logical storage pools. Using the +:term:`CRUSH` algorithm, Ceph calculates which placement group (PG) should +contain the object, and which OSD should store the placement group. The +CRUSH algorithm enables the Ceph Storage Cluster to scale, rebalance, and +recover dynamically. + +.. _REST API: ../../mgr/restful + +.. container:: columns-2 + + .. container:: column + + .. raw:: html + + <h3>Recommendations</h3> + + To begin using Ceph in production, you should review our hardware + recommendations and operating system recommendations. + + .. toctree:: + :maxdepth: 2 + + Hardware Recommendations <hardware-recommendations> + OS Recommendations <os-recommendations> + + .. container:: column + + .. raw:: html + + <h3>Get Involved</h3> + + You can avail yourself of help or contribute documentation, source + code or bugs by getting involved in the Ceph community. + + .. toctree:: + :maxdepth: 2 + + get-involved + documenting-ceph |