mirror of
https://github.com/ceph/ceph
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a78fe85470
Explain the initialism "OSD" and link to its definition in the glossary.
This PR is raised in response to an anonymous documentation bug that reads
"Paragraph 2 uses the acronym OSD without any explanation.
This makes it very difficult to understand this part of
the documentation as there is no indication of what this
acronym is until much further into the documentation. Replace
first occurence of OSD with Object Storage Daemon (OSD) or
link it to the glossary."
-- https://pad.ceph.com/p/Report_Documentation_Bugs
Co-authored-by: Anthony D'Atri <anthony.datri@gmail.com>
Signed-off-by: Zac Dover <zac.dover@proton.me>
100 lines
3.8 KiB
ReStructuredText
100 lines
3.8 KiB
ReStructuredText
===============
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Intro to Ceph
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===============
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Ceph can be used to provide :term:`Ceph Object Storage` to :term:`Cloud
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Platforms` and Ceph can be used to provide :term:`Ceph Block Device` services
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to :term:`Cloud Platforms`. Ceph can be used to deploy a :term:`Ceph File
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System`. All :term:`Ceph Storage Cluster` deployments begin with setting up
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each :term:`Ceph Node` and then setting up the network.
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A Ceph Storage Cluster requires the following: at least one Ceph Monitor and at
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least one Ceph Manager, and at least as many :term:`Ceph Object Storage
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Daemon<Ceph OSD>`\s (OSDs) as there are copies of a given object stored in the
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Ceph cluster (for example, if three copies of a given object are stored in the
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Ceph cluster, then at least three OSDs must exist in that Ceph cluster).
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The Ceph Metadata Server is necessary to run Ceph File System clients.
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.. note::
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It is a best practice to have a Ceph Manager for each Monitor, but it is not
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necessary.
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.. ditaa::
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+---------------+ +------------+ +------------+ +---------------+
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| OSDs | | Monitors | | Managers | | MDSs |
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+---------------+ +------------+ +------------+ +---------------+
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- **Monitors**: A :term:`Ceph Monitor` (``ceph-mon``) maintains maps
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of the cluster state, including the monitor map, manager map, the
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OSD map, the MDS map, and the CRUSH map. These maps are critical
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cluster state required for Ceph daemons to coordinate with each other.
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Monitors are also responsible for managing authentication between
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daemons and clients. At least three monitors are normally required
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for redundancy and high availability.
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- **Managers**: A :term:`Ceph Manager` daemon (``ceph-mgr``) is
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responsible for keeping track of runtime metrics and the current
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state of the Ceph cluster, including storage utilization, current
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performance metrics, and system load. The Ceph Manager daemons also
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host python-based modules to manage and expose Ceph cluster
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information, including a web-based :ref:`mgr-dashboard` and
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`REST API`_. At least two managers are normally required for high
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availability.
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- **Ceph OSDs**: An Object Storage Daemon (:term:`Ceph OSD`,
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``ceph-osd``) stores data, handles data replication, recovery,
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rebalancing, and provides some monitoring information to Ceph
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Monitors and Managers by checking other Ceph OSD Daemons for a
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heartbeat. At least three Ceph OSDs are normally required for
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redundancy and high availability.
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- **MDSs**: A :term:`Ceph Metadata Server` (MDS, ``ceph-mds``) stores
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metadata on behalf of the :term:`Ceph File System` (i.e., Ceph Block
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Devices and Ceph Object Storage do not use MDS). Ceph Metadata
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Servers allow POSIX file system users to execute basic commands (like
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``ls``, ``find``, etc.) without placing an enormous burden on the
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Ceph Storage Cluster.
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Ceph stores data as objects within logical storage pools. Using the
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:term:`CRUSH` algorithm, Ceph calculates which placement group (PG) should
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contain the object, and which OSD should store the placement group. The
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CRUSH algorithm enables the Ceph Storage Cluster to scale, rebalance, and
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recover dynamically.
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.. _REST API: ../../mgr/restful
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.. container:: columns-2
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.. container:: column
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.. raw:: html
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<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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.. container:: column
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.. raw:: html
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<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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:maxdepth: 2
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get-involved
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documenting-ceph
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