[ceph.git] / ceph / doc / glossary.rst

===============
 Ceph Glossary
===============

.. glossary::

        Application
                More properly called a :term:`client`, an application is any program
                external to Ceph that uses a Ceph Cluster to store and
                replicate data.

	:ref:`BlueStore<rados_config_storage_devices_bluestore>`
                OSD BlueStore is a storage back end used by OSD daemons, and
                was designed specifically for use with Ceph. BlueStore was
                introduced in the Ceph Kraken release. In the Ceph Luminous
                release, BlueStore became Ceph's default storage back end,
                supplanting FileStore. Unlike :term:`filestore`, BlueStore
                stores objects directly on Ceph block devices without any file
                system interface. Since Luminous (12.2), BlueStore has been
                Ceph's default and recommended storage back end.

        Bucket
                In the context of :term:`RGW`, a bucket is a group of objects.
                In a filesystem-based analogy in which objects are the
                counterpart of files, buckets are the counterpart of
                directories. :ref:`Multisite sync
                policies<radosgw-multisite-sync-policy>` can be set on buckets,
                to provide fine-grained control of data movement from one zone
                to another zone. 
                
                The concept of the bucket has been taken from AWS S3. See also
                `the AWS S3 page on creating buckets <https://docs.aws.amazon.com/AmazonS3/latest/userguide/creating-buckets-s3.html>`_
                and `the AWS S3 'Buckets Overview' page <https://docs.aws.amazon.com/AmazonS3/latest/userguide/UsingBucket.html>`_.

                OpenStack Swift uses the term "containers" for what RGW and AWS call "buckets". 
                See `the OpenStack Storage API overview page <https://docs.openstack.org/swift/latest/api/object_api_v1_overview.html>`_.
                
	Ceph
                Ceph is a distributed network storage and file system with
                distributed metadata management and POSIX semantics.

	Ceph Block Device
                A software instrument that orchestrates the storage of
                block-based data in Ceph. Ceph Block Device (also called "RBD",
                or "RADOS block device") splits block-based application data
                into "chunks". RADOS stores these chunks as objects. Ceph Block
                Device orchestrates the storage of those objects across the
                storage cluster. See also :term:`RBD`.

	Ceph Block Storage
                One of the three kinds of storage supported by Ceph (the other
                two are object storage and file storage). Ceph Block Storage is
                the block storage "product", which refers to block-storage
                related services and capabilities when used in conjunction with
                the collection of (1) ``librbd`` (a python module that provides
                file-like access to :term:`RBD` images), (2) a hypervisor such
                as QEMU or Xen, and (3) a hypervisor abstraction layer such as
                ``libvirt``.

	Ceph Client
                Any of the Ceph components that can access a Ceph Storage
                Cluster. This includes the Ceph Object Gateway, the Ceph Block
                Device, the Ceph File System, and their corresponding
                libraries. It also includes kernel modules, and FUSEs
                (Filesystems in USERspace).

	Ceph Client Libraries
                The collection of libraries that can be used to interact with
                components of the Ceph Cluster.

	Ceph Cluster Map
                See :term:`Cluster Map`

	Ceph Dashboard
                :ref:`The Ceph Dashboard<mgr-dashboard>` is a built-in
                web-based Ceph management and monitoring application through
                which you can inspect and administer various resources within
                the cluster. It is implemented as a :ref:`ceph-manager-daemon`
                module.

	Ceph File System
                See :term:`CephFS`

	:ref:`CephFS<ceph-file-system>`
                The **Ceph F**\ile **S**\ystem, or CephFS, is a
                POSIX-compliant file system built on top of Ceph’s distributed
                object store, RADOS.  See :ref:`CephFS Architecture
                <arch-cephfs>` for more details.

	Ceph Interim Release
                See :term:`Releases`.

	Ceph Kernel Modules
                The collection of kernel modules that can be used to interact
                with the Ceph Cluster (for example: ``ceph.ko``, ``rbd.ko``).

	:ref:`Ceph Manager<ceph-manager-daemon>`
                The Ceph manager daemon (ceph-mgr) is a daemon that runs
                alongside monitor daemons to provide monitoring and interfacing
                to external monitoring and management systems. Since the
                Luminous release (12.x), no Ceph cluster functions properly
                unless it contains a running ceph-mgr daemon. 

	Ceph Manager Dashboard
                See :term:`Ceph Dashboard`.

	Ceph Metadata Server
                See :term:`MDS`.

	Ceph Monitor
                A daemon that maintains a map of the state of the cluster. This
                "cluster state" includes the monitor map, the manager map, the
                OSD map, and the CRUSH map. A Ceph cluster must contain a
                minimum of three running monitors in order to be both redundant
                and highly-available. Ceph monitors and the nodes on which they
                run are often referred to as "mon"s. See :ref:`Monitor Config
                Reference <monitor-config-reference>`.

	Ceph Node
               A Ceph node is a unit of the Ceph Cluster that communicates with
               other nodes in the Ceph Cluster in order to replicate and
               redistribute data. All of the nodes together are called the
               :term:`Ceph Storage Cluster`. Ceph nodes include :term:`OSD`\s,
               :term:`Ceph Monitor`\s, :term:`Ceph Manager`\s, and
               :term:`MDS`\es. The term "node" is usually equivalent to "host"
               in the Ceph documentation. If you have a running Ceph Cluster,
               you can list all of the nodes in it by running the command
               ``ceph node ls all``.
                
	:ref:`Ceph Object Gateway<object-gateway>`
                An object storage interface built on top of librados. Ceph
                Object Gateway provides a RESTful gateway between applications
                and Ceph storage clusters.

	Ceph Object Storage
                See :term:`Ceph Object Store`.

	Ceph Object Store
                A Ceph Object Store consists of a :term:`Ceph Storage Cluster`
                and a :term:`Ceph Object Gateway` (RGW).

	:ref:`Ceph OSD<rados_configuration_storage-devices_ceph_osd>`
                Ceph **O**\bject **S**\torage **D**\aemon. The Ceph OSD
                software, which interacts with logical disks (:term:`OSD`).
                Around 2013, there was an attempt by "research and industry"
                (Sage's own words) to insist on using the term "OSD" to mean
                only "Object Storage Device", but the Ceph community has always
                persisted in using the term to mean "Object Storage Daemon" and
                no less an authority than Sage Weil himself confirms in
                November of 2022 that "Daemon is more accurate for how Ceph is
                built" (private correspondence between Zac Dover and Sage Weil,
                07 Nov 2022). 

	Ceph OSD Daemon
                See :term:`Ceph OSD`.

	Ceph OSD Daemons
                See :term:`Ceph OSD`.

	Ceph Platform
                All Ceph software, which includes any piece of code hosted at
                `https://github.com/ceph`_.

	Ceph Point Release
                See :term:`Releases`.

	Ceph Project
                The aggregate term for the people, software, mission and
                infrastructure of Ceph.

	Ceph Release
                See :term:`Releases`.

	Ceph Release Candidate
                See :term:`Releases`.

	Ceph Stable Release
                See :term:`Releases`.

	Ceph Stack
		A collection of two or more components of Ceph.

	:ref:`Ceph Storage Cluster<arch-ceph-storage-cluster>`
                The collection of :term:`Ceph Monitor`\s, :term:`Ceph
                Manager`\s, :term:`Ceph Metadata Server`\s, and :term:`OSD`\s
                that work together to store and replicate data for use by
                applications, Ceph Users, and :term:`Ceph Client`\s. Ceph
                Storage Clusters receive data from :term:`Ceph Client`\s.

	cephx
                The Ceph authentication protocol. Cephx operates like Kerberos,
                but it has no single point of failure.

	Client
                A client is any program external to Ceph that uses a Ceph
                Cluster to store and replicate data. 

	Cloud Platforms
	Cloud Stacks
                Third party cloud provisioning platforms such as OpenStack,
                CloudStack, OpenNebula, and Proxmox VE.

	Cluster Map
                The set of maps consisting of the monitor map, OSD map, PG map,
                MDS map, and CRUSH map, which together report the state of the
                Ceph cluster. See :ref:`the "Cluster Map" section of the
                Architecture document<architecture_cluster_map>` for details.

	CRUSH
                Controlled Replication Under Scalable Hashing. It is the
                algorithm Ceph uses to compute object storage locations.

	CRUSH rule
                The CRUSH data placement rule that applies to a particular
                pool(s).

        DAS
                **D**\irect-\ **A**\ttached **S**\torage. Storage that is
                attached directly to the computer accessing it, without passing
                through a network.  Contrast with NAS and SAN.

	:ref:`Dashboard<mgr-dashboard>`
                A built-in web-based Ceph management and monitoring application
                to administer various aspects and objects of the cluster. The
                dashboard is implemented as a Ceph Manager module. See
                :ref:`mgr-dashboard` for more details.

	Dashboard Module
                Another name for :term:`Dashboard`.

	Dashboard Plugin
	filestore
                A back end for OSD daemons, where a Journal is needed and files
                are written to the filesystem.

        FQDN
                **F**\ully **Q**\ualified **D**\omain **N**\ame. A domain name
                that is applied to a node in a network and that specifies the
                node's exact location in the tree hierarchy of the DNS.

                In the context of Ceph cluster administration, FQDNs are often
                applied to hosts. In this documentation, the term "FQDN" is
                used mostly to distinguish between FQDNs and relatively simpler
                hostnames, which do not specify the exact location of the host
                in the tree hierarchy of the DNS but merely name the host.

	Host
                Any single machine or server in a Ceph Cluster. See :term:`Ceph
                Node`.

	LVM tags
                Extensible metadata for LVM volumes and groups. It is used to
                store Ceph-specific information about devices and its
                relationship with OSDs.

	:ref:`MDS<cephfs_add_remote_mds>`
                The Ceph **M**\eta\ **D**\ata **S**\erver daemon. Also referred
                to as "ceph-mds". The Ceph metadata server daemon must be
                running in any Ceph cluster that runs the CephFS file system.
                The MDS stores all filesystem metadata. 

	MGR
                The Ceph manager software, which collects all the state from
                the whole cluster in one place.

	MON
		The Ceph monitor software.

	Node
                See :term:`Ceph Node`.

	Object Storage Device
                See :term:`OSD`.

	OSD
                Probably :term:`Ceph OSD`, but not necessarily. Sometimes
                (especially in older correspondence, and especially in
                documentation that is not written specifically for Ceph), "OSD"
                means "**O**\bject **S**\torage **D**\evice", which refers to a
                physical or logical storage unit (for example: LUN). The Ceph
                community has always used the term "OSD" to refer to
                :term:`Ceph OSD Daemon` despite an industry push in the
                mid-2010s to insist that "OSD" should refer to "Object Storage
                Device", so it is important to know which meaning is intended. 

	OSD fsid
                This is a unique identifier used to identify an OSD. It is
                found in the OSD path in a file called ``osd_fsid``. The
                term ``fsid`` is used interchangeably with ``uuid``

	OSD id
                The integer that defines an OSD. It is generated by the
                monitors during the creation of each OSD.

	OSD uuid
                This is the unique identifier of an OSD. This term is used
                interchangeably with ``fsid``

        Period
                In the context of :term:`RGW`, a period is the configuration
                state of the :term:`Realm`. The period stores the configuration
                state of a multi-site configuration. When the period is updated,
                the "epoch" is said thereby to have been changed.

	:ref:`Pool<rados_pools>`
		A pool is a logical partition used to store objects.

	Pools
                See :term:`pool`.

	RADOS
                **R**\eliable **A**\utonomic **D**\istributed **O**\bject
                **S**\tore. RADOS is the object store that provides a scalable
                service for variably-sized objects. The RADOS object store is
                the core component of a Ceph cluster.  `This blog post from
                2009
                <https://ceph.io/en/news/blog/2009/the-rados-distributed-object-store/>`_
                provides a beginner's introduction to RADOS. Readers interested
                in a deeper understanding of RADOS are directed to `RADOS: A
                Scalable, Reliable Storage Service for Petabyte-scale Storage
                Clusters <https://ceph.io/assets/pdfs/weil-rados-pdsw07.pdf>`_.

	RADOS Cluster
                A proper subset of the Ceph Cluster consisting of
                :term:`OSD`\s, :term:`Ceph Monitor`\s, and :term:`Ceph
                Manager`\s.
                
	RADOS Gateway
                See :term:`RGW`.

	RBD
                The block storage component of Ceph. Also called "RADOS Block
                Device" or :term:`Ceph Block Device`.

        :ref:`Realm<rgw-realms>`
                In the context of RADOS Gateway (RGW), a realm is a globally
                unique namespace that consists of one or more zonegroups.

        Releases

	        Ceph Interim Release
                        A version of Ceph that has not yet been put through
                        quality assurance testing. May contain new features.

                Ceph Point Release
                        Any ad hoc release that includes only bug fixes and
                        security fixes.

                Ceph Release
                        Any distinct numbered version of Ceph.

                Ceph Release Candidate
                        A major version of Ceph that has undergone initial
                        quality assurance testing and is ready for beta
                        testers.

                Ceph Stable Release
                        A major version of Ceph where all features from the
                        preceding interim releases have been put through
                        quality assurance testing successfully.

	Reliable Autonomic Distributed Object Store
                The core set of storage software which stores the user's data
                (MON+OSD). See also :term:`RADOS`.

	:ref:`RGW<object-gateway>`
                **R**\ADOS **G**\ate **W**\ay.

                The component of Ceph that provides a gateway to both the
                Amazon S3 RESTful API and the OpenStack Swift API. Also called
                "RADOS Gateway" and "Ceph Object Gateway".

        secrets
                Secrets are credentials used to perform digital authentication
                whenever privileged users must access systems that require
                authentication. Secrets can be passwords, API keys, tokens, SSH
                keys, private certificates, or encryption keys.

        SDS
                Software-defined storage.

	systemd oneshot
                A systemd ``type`` where a command is defined in ``ExecStart``
                which will exit upon completion (it is not intended to
                daemonize)

	Teuthology
		The collection of software that performs scripted tests on Ceph.

        Zone
                In the context of :term:`RGW`, a zone is a logical group that
                consists of one or more :term:`RGW` instances.  A zone's
                configuration state is stored in the :term:`period`. See
                :ref:`Zones<radosgw-zones>`.

.. _https://github.com/ceph: https://github.com/ceph
.. _Cluster Map: ../architecture#cluster-map
Commit	Line	Data
7c673cae FG	1	===============
	2	Ceph Glossary
	3	===============
	4
39ae355f	5	.. glossary::
7c673cae	6
39ae355f TL	7	Application
	8	More properly called a :term:`client`, an application is any program
	9	external to Ceph that uses a Ceph Cluster to store and
	10	replicate data.
	11
	12	:ref:`BlueStore<rados_config_storage_devices_bluestore>`
	13	OSD BlueStore is a storage back end used by OSD daemons, and
	14	was designed specifically for use with Ceph. BlueStore was
	15	introduced in the Ceph Kraken release. In the Ceph Luminous
	16	release, BlueStore became Ceph's default storage back end,
	17	supplanting FileStore. Unlike :term:`filestore`, BlueStore
	18	stores objects directly on Ceph block devices without any file
	19	system interface. Since Luminous (12.2), BlueStore has been
	20	Ceph's default and recommended storage back end.
	21
	22	Bucket
	23	In the context of :term:`RGW`, a bucket is a group of objects.
	24	In a filesystem-based analogy in which objects are the
	25	counterpart of files, buckets are the counterpart of
	26	directories. :ref:`Multisite sync
	27	policies<radosgw-multisite-sync-policy>` can be set on buckets,
	28	to provide fine-grained control of data movement from one zone
	29	to another zone.
	30
	31	The concept of the bucket has been taken from AWS S3. See also
	32	`the AWS S3 page on creating buckets <https://docs.aws.amazon.com/AmazonS3/latest/userguide/creating-buckets-s3.html>`_
	33	and `the AWS S3 'Buckets Overview' page <https://docs.aws.amazon.com/AmazonS3/latest/userguide/UsingBucket.html>`_.
	34
	35	OpenStack Swift uses the term "containers" for what RGW and AWS call "buckets".
	36	See `the OpenStack Storage API overview page <https://docs.openstack.org/swift/latest/api/object_api_v1_overview.html>`_.
	37
	38	Ceph
	39	Ceph is a distributed network storage and file system with
	40	distributed metadata management and POSIX semantics.
7c673cae	41
39ae355f TL	42	Ceph Block Device
	43	A software instrument that orchestrates the storage of
	44	block-based data in Ceph. Ceph Block Device (also called "RBD",
	45	or "RADOS block device") splits block-based application data
	46	into "chunks". RADOS stores these chunks as objects. Ceph Block
	47	Device orchestrates the storage of those objects across the
	48	storage cluster. See also :term:`RBD`.
7c673cae	49
39ae355f TL	50	Ceph Block Storage
	51	One of the three kinds of storage supported by Ceph (the other
	52	two are object storage and file storage). Ceph Block Storage is
	53	the block storage "product", which refers to block-storage
	54	related services and capabilities when used in conjunction with
	55	the collection of (1) ``librbd`` (a python module that provides
	56	file-like access to :term:`RBD` images), (2) a hypervisor such
	57	as QEMU or Xen, and (3) a hypervisor abstraction layer such as
	58	``libvirt``.
7c673cae	59
39ae355f TL	60	Ceph Client
	61	Any of the Ceph components that can access a Ceph Storage
	62	Cluster. This includes the Ceph Object Gateway, the Ceph Block
	63	Device, the Ceph File System, and their corresponding
	64	libraries. It also includes kernel modules, and FUSEs
	65	(Filesystems in USERspace).
b5b8bbf5	66
39ae355f TL	67	Ceph Client Libraries
	68	The collection of libraries that can be used to interact with
	69	components of the Ceph Cluster.
7c673cae	70
39ae355f TL	71	Ceph Cluster Map
39ae355f TL	72	See :term:`Cluster Map`
b5b8bbf5	73
39ae355f TL	74	Ceph Dashboard
	75	:ref:`The Ceph Dashboard<mgr-dashboard>` is a built-in
	76	web-based Ceph management and monitoring application through
	77	which you can inspect and administer various resources within
	78	the cluster. It is implemented as a :ref:`ceph-manager-daemon`
	79	module.
	80
	81	Ceph File System
	82	See :term:`CephFS`
	83
	84	:ref:`CephFS<ceph-file-system>`
	85	The Ceph F\ile S\ystem, or CephFS, is a
	86	POSIX-compliant file system built on top of Ceph’s distributed
	87	object store, RADOS. See :ref:`CephFS Architecture
	88	<arch-cephfs>` for more details.
	89
	90	Ceph Interim Release
	91	See :term:`Releases`.
	92
	93	Ceph Kernel Modules
	94	The collection of kernel modules that can be used to interact
	95	with the Ceph Cluster (for example: ``ceph.ko``, ``rbd.ko``).
	96
	97	:ref:`Ceph Manager<ceph-manager-daemon>`
	98	The Ceph manager daemon (ceph-mgr) is a daemon that runs
	99	alongside monitor daemons to provide monitoring and interfacing
	100	to external monitoring and management systems. Since the
	101	Luminous release (12.x), no Ceph cluster functions properly
	102	unless it contains a running ceph-mgr daemon.
	103
	104	Ceph Manager Dashboard
	105	See :term:`Ceph Dashboard`.
	106
	107	Ceph Metadata Server
	108	See :term:`MDS`.
	109
	110	Ceph Monitor
	111	A daemon that maintains a map of the state of the cluster. This
	112	"cluster state" includes the monitor map, the manager map, the
	113	OSD map, and the CRUSH map. A Ceph cluster must contain a
	114	minimum of three running monitors in order to be both redundant
	115	and highly-available. Ceph monitors and the nodes on which they
	116	run are often referred to as "mon"s. See :ref:`Monitor Config
	117	Reference <monitor-config-reference>`.
7c673cae FG	118
7c673cae FG	119	Ceph Node
39ae355f TL	120	A Ceph node is a unit of the Ceph Cluster that communicates with
	121	other nodes in the Ceph Cluster in order to replicate and
	122	redistribute data. All of the nodes together are called the
	123	:term:`Ceph Storage Cluster`. Ceph nodes include :term:`OSD`\s,
	124	:term:`Ceph Monitor`\s, :term:`Ceph Manager`\s, and
	125	:term:`MDS`\es. The term "node" is usually equivalent to "host"
	126	in the Ceph documentation. If you have a running Ceph Cluster,
	127	you can list all of the nodes in it by running the command
	128	``ceph node ls all``.
	129
	130	:ref:`Ceph Object Gateway<object-gateway>`
	131	An object storage interface built on top of librados. Ceph
	132	Object Gateway provides a RESTful gateway between applications
	133	and Ceph storage clusters.
	134
	135	Ceph Object Storage
	136	See :term:`Ceph Object Store`.
b5b8bbf5	137
7c673cae	138	Ceph Object Store
39ae355f TL	139	A Ceph Object Store consists of a :term:`Ceph Storage Cluster`
	140	and a :term:`Ceph Object Gateway` (RGW).
	141
	142	:ref:`Ceph OSD<rados_configuration_storage-devices_ceph_osd>`
	143	Ceph O\bject S\torage D\aemon. The Ceph OSD
	144	software, which interacts with logical disks (:term:`OSD`).
	145	Around 2013, there was an attempt by "research and industry"
	146	(Sage's own words) to insist on using the term "OSD" to mean
	147	only "Object Storage Device", but the Ceph community has always
	148	persisted in using the term to mean "Object Storage Daemon" and
	149	no less an authority than Sage Weil himself confirms in
	150	November of 2022 that "Daemon is more accurate for how Ceph is
	151	built" (private correspondence between Zac Dover and Sage Weil,
	152	07 Nov 2022).
7c673cae	153
39ae355f TL	154	Ceph OSD Daemon
39ae355f TL	155	See :term:`Ceph OSD`.
7c673cae	156
39ae355f TL	157	Ceph OSD Daemons
39ae355f TL	158	See :term:`Ceph OSD`.
7c673cae	159
39ae355f TL	160	Ceph Platform
	161	All Ceph software, which includes any piece of code hosted at
	162	`https://github.com/ceph`_.
b5b8bbf5	163
39ae355f TL	164	Ceph Point Release
39ae355f TL	165	See :term:`Releases`.
b5b8bbf5	166
39ae355f TL	167	Ceph Project
	168	The aggregate term for the people, software, mission and
	169	infrastructure of Ceph.
7c673cae	170
39ae355f TL	171	Ceph Release
	172	See :term:`Releases`.
	173
	174	Ceph Release Candidate
	175	See :term:`Releases`.
	176
	177	Ceph Stable Release
	178	See :term:`Releases`.
	179
	180	Ceph Stack
	181	A collection of two or more components of Ceph.
	182
	183	:ref:`Ceph Storage Cluster<arch-ceph-storage-cluster>`
	184	The collection of :term:`Ceph Monitor`\s, :term:`Ceph
	185	Manager`\s, :term:`Ceph Metadata Server`\s, and :term:`OSD`\s
	186	that work together to store and replicate data for use by
	187	applications, Ceph Users, and :term:`Ceph Client`\s. Ceph
	188	Storage Clusters receive data from :term:`Ceph Client`\s.
	189
	190	cephx
	191	The Ceph authentication protocol. Cephx operates like Kerberos,
	192	but it has no single point of failure.
	193
	194	Client
	195	A client is any program external to Ceph that uses a Ceph
	196	Cluster to store and replicate data.
7c673cae FG	197
	198	Cloud Platforms
	199	Cloud Stacks
39ae355f TL	200	Third party cloud provisioning platforms such as OpenStack,
39ae355f TL	201	CloudStack, OpenNebula, and Proxmox VE.
7c673cae	202
39ae355f TL	203	Cluster Map
	204	The set of maps consisting of the monitor map, OSD map, PG map,
	205	MDS map, and CRUSH map, which together report the state of the
	206	Ceph cluster. See :ref:`the "Cluster Map" section of the
	207	Architecture document<architecture_cluster_map>` for details.
b5b8bbf5	208
39ae355f TL	209	CRUSH
	210	Controlled Replication Under Scalable Hashing. It is the
	211	algorithm Ceph uses to compute object storage locations.
b5b8bbf5	212
39ae355f TL	213	CRUSH rule
	214	The CRUSH data placement rule that applies to a particular
	215	pool(s).
b5b8bbf5	216
39ae355f TL	217	DAS
	218	D\irect-\ A\ttached S\torage. Storage that is
	219	attached directly to the computer accessing it, without passing
	220	through a network. Contrast with NAS and SAN.
b5b8bbf5	221
39ae355f TL	222	:ref:`Dashboard<mgr-dashboard>`
	223	A built-in web-based Ceph management and monitoring application
	224	to administer various aspects and objects of the cluster. The
	225	dashboard is implemented as a Ceph Manager module. See
	226	:ref:`mgr-dashboard` for more details.
b5b8bbf5	227
39ae355f TL	228	Dashboard Module
39ae355f TL	229	Another name for :term:`Dashboard`.
b5b8bbf5	230
39ae355f	231	Dashboard Plugin
b5b8bbf5	232	filestore
39ae355f TL	233	A back end for OSD daemons, where a Journal is needed and files
	234	are written to the filesystem.
	235
	236	FQDN
	237	F\ully Q\ualified D\omain N\ame. A domain name
	238	that is applied to a node in a network and that specifies the
	239	node's exact location in the tree hierarchy of the DNS.
	240
	241	In the context of Ceph cluster administration, FQDNs are often
	242	applied to hosts. In this documentation, the term "FQDN" is
	243	used mostly to distinguish between FQDNs and relatively simpler
	244	hostnames, which do not specify the exact location of the host
	245	in the tree hierarchy of the DNS but merely name the host.
	246
	247	Host
	248	Any single machine or server in a Ceph Cluster. See :term:`Ceph
	249	Node`.
	250
	251	LVM tags
	252	Extensible metadata for LVM volumes and groups. It is used to
	253	store Ceph-specific information about devices and its
	254	relationship with OSDs.
	255
	256	:ref:`MDS<cephfs_add_remote_mds>`
	257	The Ceph M\eta\ D\ata S\erver daemon. Also referred
	258	to as "ceph-mds". The Ceph metadata server daemon must be
	259	running in any Ceph cluster that runs the CephFS file system.
	260	The MDS stores all filesystem metadata.
	261
	262	MGR
	263	The Ceph manager software, which collects all the state from
	264	the whole cluster in one place.
b5b8bbf5	265
7c673cae FG	266	MON
	267	The Ceph monitor software.
	268
39ae355f TL	269	Node
39ae355f TL	270	See :term:`Ceph Node`.
7c673cae	271
39ae355f TL	272	Object Storage Device
39ae355f TL	273	See :term:`OSD`.
11fdf7f2	274
39ae355f TL	275	OSD
	276	Probably :term:`Ceph OSD`, but not necessarily. Sometimes
	277	(especially in older correspondence, and especially in
	278	documentation that is not written specifically for Ceph), "OSD"
	279	means "O\bject S\torage D\evice", which refers to a
	280	physical or logical storage unit (for example: LUN). The Ceph
	281	community has always used the term "OSD" to refer to
	282	:term:`Ceph OSD Daemon` despite an industry push in the
	283	mid-2010s to insist that "OSD" should refer to "Object Storage
	284	Device", so it is important to know which meaning is intended.
7c673cae	285
39ae355f TL	286	OSD fsid
	287	This is a unique identifier used to identify an OSD. It is
	288	found in the OSD path in a file called ``osd_fsid``. The
	289	term ``fsid`` is used interchangeably with ``uuid``
7c673cae	290
39ae355f TL	291	OSD id
	292	The integer that defines an OSD. It is generated by the
	293	monitors during the creation of each OSD.
7c673cae	294
39ae355f TL	295	OSD uuid
	296	This is the unique identifier of an OSD. This term is used
	297	interchangeably with ``fsid``
7c673cae	298
39ae355f TL	299	Period
	300	In the context of :term:`RGW`, a period is the configuration
	301	state of the :term:`Realm`. The period stores the configuration
	302	state of a multi-site configuration. When the period is updated,
	303	the "epoch" is said thereby to have been changed.
b5b8bbf5	304
39ae355f TL	305	:ref:`Pool<rados_pools>`
39ae355f TL	306	A pool is a logical partition used to store objects.
7c673cae	307
39ae355f TL	308	Pools
39ae355f TL	309	See :term:`pool`.
7c673cae	310
39ae355f TL	311	RADOS
	312	R\eliable A\utonomic D\istributed O\bject
	313	S\tore. RADOS is the object store that provides a scalable
	314	service for variably-sized objects. The RADOS object store is
	315	the core component of a Ceph cluster. `This blog post from
	316	2009
	317	<https://ceph.io/en/news/blog/2009/the-rados-distributed-object-store/>`_
	318	provides a beginner's introduction to RADOS. Readers interested
	319	in a deeper understanding of RADOS are directed to `RADOS: A
	320	Scalable, Reliable Storage Service for Petabyte-scale Storage
	321	Clusters <https://ceph.io/assets/pdfs/weil-rados-pdsw07.pdf>`_.
7c673cae	322
39ae355f TL	323	RADOS Cluster
	324	A proper subset of the Ceph Cluster consisting of
	325	:term:`OSD`\s, :term:`Ceph Monitor`\s, and :term:`Ceph
	326	Manager`\s.
	327
	328	RADOS Gateway
	329	See :term:`RGW`.
7c673cae	330
39ae355f TL	331	RBD
	332	The block storage component of Ceph. Also called "RADOS Block
	333	Device" or :term:`Ceph Block Device`.
7c673cae	334
39ae355f TL	335	:ref:`Realm<rgw-realms>`
	336	In the context of RADOS Gateway (RGW), a realm is a globally
	337	unique namespace that consists of one or more zonegroups.
b5b8bbf5	338
39ae355f	339	Releases
7c673cae	340
39ae355f TL	341	Ceph Interim Release
	342	A version of Ceph that has not yet been put through
	343	quality assurance testing. May contain new features.
	344
	345	Ceph Point Release
	346	Any ad hoc release that includes only bug fixes and
	347	security fixes.
	348
	349	Ceph Release
	350	Any distinct numbered version of Ceph.
	351
	352	Ceph Release Candidate
	353	A major version of Ceph that has undergone initial
	354	quality assurance testing and is ready for beta
	355	testers.
	356
	357	Ceph Stable Release
	358	A major version of Ceph where all features from the
	359	preceding interim releases have been put through
	360	quality assurance testing successfully.
	361
	362	Reliable Autonomic Distributed Object Store
	363	The core set of storage software which stores the user's data
	364	(MON+OSD). See also :term:`RADOS`.
	365
	366	:ref:`RGW<object-gateway>`
	367	R\ADOS G\ate W\ay.
	368
	369	The component of Ceph that provides a gateway to both the
	370	Amazon S3 RESTful API and the OpenStack Swift API. Also called
	371	"RADOS Gateway" and "Ceph Object Gateway".
	372
	373	secrets
	374	Secrets are credentials used to perform digital authentication
	375	whenever privileged users must access systems that require
	376	authentication. Secrets can be passwords, API keys, tokens, SSH
	377	keys, private certificates, or encryption keys.
	378
	379	SDS
	380	Software-defined storage.
7c673cae	381
b5b8bbf5	382	systemd oneshot
39ae355f TL	383	A systemd ``type`` where a command is defined in ``ExecStart``
	384	which will exit upon completion (it is not intended to
	385	daemonize)
b5b8bbf5	386
39ae355f TL	387	Teuthology
	388	The collection of software that performs scripted tests on Ceph.
	389
	390	Zone
	391	In the context of :term:`RGW`, a zone is a logical group that
	392	consists of one or more :term:`RGW` instances. A zone's
	393	configuration state is stored in the :term:`period`. See
	394	:ref:`Zones<radosgw-zones>`.
b5b8bbf5	395
11fdf7f2	396	.. _https://github.com/ceph: https://github.com/ceph
39ae355f	397	.. _Cluster Map: ../architecture#cluster-map