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https://github.com/ceph/ceph
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71 lines
2.8 KiB
ReStructuredText
71 lines
2.8 KiB
ReStructuredText
===============
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Intro to Ceph
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===============
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Whether you want to provide :term:`Ceph Object Storage` and/or :term:`Ceph Block
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Device` services to :term:`Cloud Platforms`, deploy a :term:`Ceph Filesystem` or
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use Ceph for another purpose, all :term:`Ceph Storage Cluster` deployments begin
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with setting up each :term:`Ceph Node`, your network and the Ceph Storage
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Cluster. A Ceph Storage Cluster requires at least one Ceph Monitor and at least
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two Ceph OSD Daemons. The Ceph Metadata Server is essential when running Ceph
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Filesystem clients.
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.. ditaa:: +---------------+ +---------------+ +---------------+
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| OSDs | | Monitor | | MDS |
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+---------------+ +---------------+ +---------------+
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- **OSDs**: A :term:`Ceph OSD Daemon` (OSD) stores data, handles data
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replication, recovery, backfilling, rebalancing, and provides some monitoring
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information to Ceph Monitors by checking other Ceph OSD Daemons for a
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heartbeat. A Ceph Storage Cluster requires at least two Ceph OSD Daemons to
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achieve an ``active + clean`` state when the cluster makes two copies of your
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data (Ceph makes 2 copies by default, but you can adjust it).
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- **Monitors**: A :term:`Ceph Monitor` maintains maps of the cluster state,
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including the monitor map, the OSD map, the Placement Group (PG) map, and the
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CRUSH map. Ceph maintains a history (called an "epoch") of each state change
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in the Ceph Monitors, Ceph OSD Daemons, and PGs.
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- **MDSs**: A :term:`Ceph Metadata Server` (MDS) stores metadata on behalf of
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the :term:`Ceph Filesystem` (i.e., Ceph Block Devices and Ceph Object Storage
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do not use MDS). Ceph Metadata Servers make it feasible for POSIX file system
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users to execute basic commands like ``ls``, ``find``, etc. without placing
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an enormous burden on the Ceph Storage Cluster.
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Ceph stores a client's data as objects within storage pools. Using the CRUSH
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algorithm, Ceph calculates which placement group should contain the object,
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and further calculates which Ceph OSD Daemon should store the placement group.
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The CRUSH algorithm enables the Ceph Storage Cluster to scale, rebalance, and
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recover dynamically.
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.. raw:: html
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<style type="text/css">div.body h3{margin:5px 0px 0px 0px;}</style>
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<table cellpadding="10"><colgroup><col width="50%"><col width="50%"></colgroup><tbody valign="top"><tr><td><h3>Recommendations</h3>
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To begin using Ceph in production, you should review our hardware
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recommendations and operating system recommendations.
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.. toctree::
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:maxdepth: 2
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Hardware Recommendations <hardware-recommendations>
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OS Recommendations <os-recommendations>
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.. raw:: html
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</td><td><h3>Get Involved</h3>
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You can avail yourself of help or contribute documentation, source
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code or bugs by getting involved in the Ceph community.
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.. toctree::
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get-involved
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.. raw:: html
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</td></tr></tbody></table>
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