initial code repo

[stor4nfv.git] / src / ceph / doc / start / intro.rst

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+===============
+ Intro to Ceph
+===============
+
+Whether you want to provide :term:`Ceph Object Storage` and/or
+:term:`Ceph Block Device` services to :term:`Cloud Platforms`, deploy
+a :term:`Ceph Filesystem` or use Ceph for another purpose, all
+:term:`Ceph Storage Cluster` deployments begin with setting up each
+:term:`Ceph Node`, your network, and the Ceph Storage Cluster. A Ceph
+Storage Cluster requires at least one Ceph Monitor, Ceph Manager, and
+Ceph OSD (Object Storage Daemon). The Ceph Metadata Server is also
+required when running Ceph Filesystem clients.
+
+.. 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, 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 plugins to manage and expose Ceph cluster
+  information, including a web-based `dashboard`_ and `REST API`_.  At
+  least two managers are normally required for high availability.
+
+- **Ceph OSDs**: A :term:`Ceph OSD` (object storage daemon,
+  ``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 3 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 Filesystem` (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 should
+contain the object, and further calculates which Ceph OSD Daemon
+should store the placement group.  The CRUSH algorithm enables the
+Ceph Storage Cluster to scale, rebalance, and recover dynamically.
+
+.. _dashboard: ../../mgr/dashboard
+.. _REST API: ../../mgr/restful
+
+.. raw:: html
+
+       <style type="text/css">div.body h3{margin:5px 0px 0px 0px;}</style>
+       <table cellpadding="10"><colgroup><col width="50%"><col width="50%"></colgroup><tbody valign="top"><tr><td><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>
+
+
+.. raw:: html 
+
+       </td><td><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
+
+.. raw:: html
+
+       </td></tr></tbody></table>