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                 `http://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 Filesystem
  70         CephFS
  71         Ceph FS
  72                 The POSIX filesystem components of Ceph.
  73
  74         Cloud Platforms
  75         Cloud Stacks
  76                 Third party cloud provisioning platforms such as OpenStack, CloudStack,
  77                 OpenNebula, ProxMox, etc.
  78
  79         Object Storage Device
  80         OSD
  81                 A physical or logical storage unit (*e.g.*, LUN).
  82                 Sometimes, Ceph users use the
  83                 term "OSD" to refer to :term:`Ceph OSD Daemon`, though the
  84                 proper term is "Ceph OSD".
  85
  86         Ceph OSD Daemon
  87         Ceph OSD Daemons
  88         Ceph OSD
  89                 The Ceph OSD software, which interacts with a logical
  90                 disk (:term:`OSD`). Sometimes, Ceph users use the
  91                 term "OSD" to refer to "Ceph OSD Daemon", though the
  92                 proper term is "Ceph OSD".
  93
  94         OSD id
  95                 The integer that defines an OSD. It is generated by the monitors as part
  96                 of the creation of a new OSD.
  97
  98         OSD fsid
  99                 This is a unique identifier used to further improve the uniqueness of an
 100                 OSD and it is found in the OSD path in a file called ``osd_fsid``. This
 101                 ``fsid`` term is used interchangeably with ``uuid``
 102
 103         OSD uuid
 104                 Just like the OSD fsid, this is the OSD unique identifer and is used
 105                 interchangeably with ``fsid``
 106
 107         bluestore
 108                 OSD BlueStore is a new back end for OSD daemons (kraken and newer
 109                 versions). Unlike :term:`filestore` it stores objects directly on the
 110                 Ceph block devices without any file system interface.
 111
 112         filestore
 113                 A back end for OSD daemons, where a Journal is needed and files are
 114                 written to the filesystem.
 115
 116         Ceph Monitor
 117         MON
 118                 The Ceph monitor software.
 119
 120         Ceph Manager
 121         MGR
 122                 The Ceph manager software, which collects all the state from the whole
 123                 cluster in one place.
 124
 125         Ceph Metadata Server
 126         MDS
 127                 The Ceph metadata software.
 128
 129         Ceph Clients
 130         Ceph Client
 131                 The collection of Ceph components which can access a Ceph Storage
 132                 Cluster. These include the Ceph Object Gateway, the Ceph Block Device,
 133                 the Ceph Filesystem, and their corresponding libraries, kernel modules,
 134                 and FUSEs.
 135
 136         Ceph Kernel Modules
 137                 The collection of kernel modules which can be used to interact with the
 138                 Ceph System (e.g,. ``ceph.ko``, ``rbd.ko``).
 139
 140         Ceph Client Libraries
 141                 The collection of libraries that can be used to interact with components
 142                 of the Ceph System.
 143
 144         Ceph Release
 145                 Any distinct numbered version of Ceph.
 146
 147         Ceph Point Release
 148                 Any ad-hoc release that includes only bug or security fixes.
 149
 150         Ceph Interim Release
 151                 Versions of Ceph that have not yet been put through quality assurance
 152                 testing, but may contain new features.
 153
 154         Ceph Release Candidate
 155                 A major version of Ceph that has undergone initial quality assurance
 156                 testing and is ready for beta testers.
 157
 158         Ceph Stable Release
 159                 A major version of Ceph where all features from the preceding interim
 160                 releases have been put through quality assurance testing successfully.
 161
 162         Ceph Test Framework
 163         Teuthology
 164                 The collection of software that performs scripted tests on Ceph.
 165
 166         CRUSH
 167                 Controlled Replication Under Scalable Hashing. It is the algorithm
 168                 Ceph uses to compute object storage locations.
 169
 170         ruleset
 171                 A set of CRUSH data placement rules that applies to a particular pool(s).
 172
 173         Pool
 174         Pools
 175                 Pools are logical partitions for storing objects.
 176
 177         systemd oneshot
 178                 A systemd ``type`` where a command is defined in ``ExecStart`` which will
 179                 exit upon completion (it is not intended to daemonize)
 180
 181         LVM tags
 182                 Extensible metadata for LVM volumes and groups. It is used to store
 183                 Ceph-specific information about devices and its relationship with
 184                 OSDs.
 185
 186 .. _http://github.com/ceph: http://github.com/ceph
 187 .. _Cluster Map: ../architecture#cluster-map