ceph/doc/glossary.rst

   1 ===============
   2  Ceph Glossary
   3 ===============
   4
   5 Ceph is growing rapidly. As firms deploy Ceph, the technical terms such as
   6 "RADOS", "RBD," "RGW" and so forth require corresponding marketing terms
   7 that explain what each component does. The terms in this glossary are
   8 intended to complement the existing technical terminology.
   9
  10 Sometimes more than one term applies to a definition. Generally, the first
  11 term reflects a term consistent with Ceph's marketing, and secondary terms
  12 reflect either technical terms or legacy ways of referring to Ceph systems.
  13
  14
  15 .. glossary::
  16
  17         Ceph Project
  18                 The aggregate term for the people, software, mission and infrastructure
  19                 of Ceph.
  20
  21         cephx
  22                 The Ceph authentication protocol. Cephx operates like Kerberos, but it
  23                 has no single point of failure.
  24
  25         Ceph
  26         Ceph Platform
  27                 All Ceph software, which includes any piece of code hosted at
  28                 `https://github.com/ceph`_.
  29
  30         Ceph System
  31         Ceph Stack
  32                 A collection of two or more components of Ceph.
  33
  34         Ceph Node
  35         Node
  36         Host
  37                 Any single machine or server in a Ceph System.
  38
  39         Ceph Storage Cluster
  40         Ceph Object Store
  41         RADOS
  42         RADOS Cluster
  43         Reliable Autonomic Distributed Object Store
  44                 The core set of storage software which stores the user's data (MON+OSD).
  45
  46         Ceph Cluster Map
  47         Cluster Map
  48                 The set of maps comprising the monitor map, OSD map, PG map, MDS map and
  49                 CRUSH map. See `Cluster Map`_ for details.
  50
  51         Ceph Object Storage
  52                 The object storage "product", service or capabilities, which consists
  53                 essentially of a Ceph Storage Cluster and a Ceph Object Gateway.
  54
  55         Ceph Object Gateway
  56         RADOS Gateway
  57         RGW
  58                 The S3/Swift gateway component of Ceph.
  59
  60         Ceph Block Device
  61         RBD
  62                 The block storage component of Ceph.
  63
  64         Ceph Block Storage
  65                 The block storage "product," service or capabilities when used in
  66                 conjunction with ``librbd``, a hypervisor such as QEMU or Xen, and a
  67                 hypervisor abstraction layer such as ``libvirt``.
  68
  69         Ceph File System
  70         CephFS
  71         Ceph FS
  72                 The POSIX filesystem components of Ceph. Refer
  73                 :ref:`CephFS Architecture <arch-cephfs>` and :ref:`ceph-file-system` for
  74                 more details.
  75
  76         Cloud Platforms
  77         Cloud Stacks
  78                 Third party cloud provisioning platforms such as OpenStack, CloudStack,
  79                 OpenNebula, Proxmox VE, etc.
  80
  81         Object Storage Device
  82         OSD
  83                 A physical or logical storage unit (*e.g.*, LUN).
  84                 Sometimes, Ceph users use the
  85                 term "OSD" to refer to :term:`Ceph OSD Daemon`, though the
  86                 proper term is "Ceph OSD".
  87
  88         Ceph OSD Daemon
  89         Ceph OSD Daemons
  90         Ceph OSD
  91                 The Ceph OSD software, which interacts with a logical
  92                 disk (:term:`OSD`). Sometimes, Ceph users use the
  93                 term "OSD" to refer to "Ceph OSD Daemon", though the
  94                 proper term is "Ceph OSD".
  95
  96         OSD id
  97                 The integer that defines an OSD. It is generated by the monitors as part
  98                 of the creation of a new OSD.
  99
 100         OSD fsid
 101                 This is a unique identifier used to further improve the uniqueness of an
 102                 OSD and it is found in the OSD path in a file called ``osd_fsid``. This
 103                 ``fsid`` term is used interchangeably with ``uuid``
 104
 105         OSD uuid
 106                 Just like the OSD fsid, this is the OSD unique identifier and is used
 107                 interchangeably with ``fsid``
 108
 109         bluestore
 110                 OSD BlueStore is a new back end for OSD daemons (kraken and newer
 111                 versions). Unlike :term:`filestore` it stores objects directly on the
 112                 Ceph block devices without any file system interface.
 113
 114         filestore
 115                 A back end for OSD daemons, where a Journal is needed and files are
 116                 written to the filesystem.
 117
 118         Ceph Monitor
 119         MON
 120                 The Ceph monitor software.
 121
 122         Ceph Manager
 123         MGR
 124                 The Ceph manager software, which collects all the state from the whole
 125                 cluster in one place.
 126
 127         Ceph Manager Dashboard
 128         Ceph Dashboard
 129         Dashboard Module
 130         Dashboard Plugin
 131         Dashboard
 132                 A built-in web-based Ceph management and monitoring application to
 133                 administer various aspects and objects of the cluster. The dashboard is
 134                 implemented as a Ceph Manager module. See :ref:`mgr-dashboard` for more
 135                 details.
 136
 137         Ceph Metadata Server
 138         MDS
 139                 The Ceph metadata software.
 140
 141         Ceph Clients
 142         Ceph Client
 143                 The collection of Ceph components which can access a Ceph Storage
 144                 Cluster. These include the Ceph Object Gateway, the Ceph Block Device,
 145                 the Ceph File System, and their corresponding libraries, kernel modules,
 146                 and FUSEs.
 147
 148         Ceph Kernel Modules
 149                 The collection of kernel modules which can be used to interact with the
 150                 Ceph System (e.g., ``ceph.ko``, ``rbd.ko``).
 151
 152         Ceph Client Libraries
 153                 The collection of libraries that can be used to interact with components
 154                 of the Ceph System.
 155
 156         Ceph Release
 157                 Any distinct numbered version of Ceph.
 158
 159         Ceph Point Release
 160                 Any ad-hoc release that includes only bug or security fixes.
 161
 162         Ceph Interim Release
 163                 Versions of Ceph that have not yet been put through quality assurance
 164                 testing, but may contain new features.
 165
 166         Ceph Release Candidate
 167                 A major version of Ceph that has undergone initial quality assurance
 168                 testing and is ready for beta testers.
 169
 170         Ceph Stable Release
 171                 A major version of Ceph where all features from the preceding interim
 172                 releases have been put through quality assurance testing successfully.
 173
 174         Ceph Test Framework
 175         Teuthology
 176                 The collection of software that performs scripted tests on Ceph.
 177
 178         CRUSH
 179                 Controlled Replication Under Scalable Hashing. It is the algorithm
 180                 Ceph uses to compute object storage locations.
 181
 182         CRUSH rule
 183                 The CRUSH data placement rule that applies to a particular pool(s).
 184
 185         Pool
 186         Pools
 187                 Pools are logical partitions for storing objects.
 188
 189         systemd oneshot
 190                 A systemd ``type`` where a command is defined in ``ExecStart`` which will
 191                 exit upon completion (it is not intended to daemonize)
 192
 193         LVM tags
 194                 Extensible metadata for LVM volumes and groups. It is used to store
 195                 Ceph-specific information about devices and its relationship with
 196                 OSDs.
 197
 198 .. _https://github.com/ceph: https://github.com/ceph
 199 .. _Cluster Map: ../architecture#cluster-map