ceph/doc/cephfs/index.rst

   1 .. _ceph-file-system:
   2
   3 =================
   4  Ceph File System
   5 =================
   6
   7 The Ceph File System, or **CephFS**, is a POSIX-compliant file system built on
   8 top of Ceph's distributed object store, **RADOS**. CephFS endeavors to provide
   9 a state-of-the-art, multi-use, highly available, and performant file store for
  10 a variety of applications, including traditional use-cases like shared home
  11 directories, HPC scratch space, and distributed workflow shared storage.
  12
  13 CephFS achieves these goals through the use of some novel architectural
  14 choices.  Notably, file metadata is stored in a separate RADOS pool from file
  15 data and served via a resizable cluster of *Metadata Servers*, or **MDS**,
  16 which may scale to support higher throughput metadata workloads.  Clients of
  17 the file system have direct access to RADOS for reading and writing file data
  18 blocks. For this reason, workloads may linearly scale with the size of the
  19 underlying RADOS object store; that is, there is no gateway or broker mediating
  20 data I/O for clients.
  21
  22 Access to data is coordinated through the cluster of MDS which serve as
  23 authorities for the state of the distributed metadata cache cooperatively
  24 maintained by clients and MDS. Mutations to metadata are aggregated by each MDS
  25 into a series of efficient writes to a journal on RADOS; no metadata state is
  26 stored locally by the MDS. This model allows for coherent and rapid
  27 collaboration between clients within the context of a POSIX file system.
  28
  29 .. image:: cephfs-architecture.svg
  30
  31 CephFS is the subject of numerous academic papers for its novel designs and
  32 contributions to file system research. It is the oldest storage interface in
  33 Ceph and was once the primary use-case for RADOS.  Now it is joined by two
  34 other storage interfaces to form a modern unified storage system: RBD (Ceph
  35 Block Devices) and RGW (Ceph Object Storage Gateway).
  36
  37
  38 Getting Started with CephFS
  39 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  40
  41 For most deployments of Ceph, setting up your first CephFS file system is as simple as:
  42
  43 .. prompt:: bash
  44
  45     # Create a CephFS volume named (for example) "cephfs":
  46     ceph fs volume create cephfs
  47
  48 The Ceph `Orchestrator`_  will automatically create and configure MDS for
  49 your file system if the back-end deployment technology supports it (see
  50 `Orchestrator deployment table`_). Otherwise, please `deploy MDS manually
  51 as needed`_. You can also `create other CephFS volumes`_.
  52
  53 Finally, to mount CephFS on your client nodes, see `Mount CephFS:
  54 Prerequisites`_ page. Additionally, a command-line shell utility is available
  55 for interactive access or scripting via the `cephfs-shell`_.
  56
  57 .. _Orchestrator: ../mgr/orchestrator
  58 .. _deploy MDS manually as needed: add-remove-mds
  59 .. _create other CephFS volumes: fs-volumes
  60 .. _Orchestrator deployment table: ../mgr/orchestrator/#current-implementation-status
  61 .. _Mount CephFS\: Prerequisites: mount-prerequisites
  62 .. _cephfs-shell: ../man/8/cephfs-shell
  63
  64
  65 .. raw:: html
  66
  67    <!---
  68
  69 Administration
  70 ^^^^^^^^^^^^^^
  71
  72 .. raw:: html
  73
  74    --->
  75
  76 .. toctree::
  77    :maxdepth: 1
  78    :hidden:
  79
  80     Create a CephFS file system <createfs>
  81     Administrative commands <administration>
  82     Creating Multiple File Systems <multifs>
  83     Provision/Add/Remove MDS(s) <add-remove-mds>
  84     MDS failover and standby configuration <standby>
  85     MDS Cache Configuration <cache-configuration>
  86     MDS Configuration Settings <mds-config-ref>
  87     Manual: ceph-mds <../../man/8/ceph-mds>
  88     Export over NFS <nfs>
  89     Application best practices <app-best-practices>
  90     FS volume and subvolumes <fs-volumes>
  91     CephFS Quotas <quota>
  92     Health messages <health-messages>
  93     Upgrading old file systems <upgrading>
  94     CephFS Top Utility <cephfs-top>
  95     Scheduled Snapshots <snap-schedule>
  96     CephFS Snapshot Mirroring <cephfs-mirroring>
  97
  98 .. raw:: html
  99
 100    <!---
 101
 102 Mounting CephFS
 103 ^^^^^^^^^^^^^^^
 104
 105 .. raw:: html
 106
 107    --->
 108
 109 .. toctree::
 110    :maxdepth: 1
 111    :hidden:
 112
 113     Client Configuration Settings <client-config-ref>
 114     Client Authentication <client-auth>
 115     Mount CephFS: Prerequisites <mount-prerequisites>
 116     Mount CephFS using Kernel Driver <mount-using-kernel-driver>
 117     Mount CephFS using FUSE <mount-using-fuse>
 118     Mount CephFS on Windows <ceph-dokan>
 119     Use the CephFS Shell <../../man/8/cephfs-shell>
 120     Supported Features of Kernel Driver <kernel-features>
 121     Manual: ceph-fuse <../../man/8/ceph-fuse>
 122     Manual: mount.ceph <../../man/8/mount.ceph>
 123     Manual: mount.fuse.ceph <../../man/8/mount.fuse.ceph>
 124
 125
 126 .. raw:: html
 127
 128    <!---
 129
 130 CephFS Concepts
 131 ^^^^^^^^^^^^^^^
 132
 133 .. raw:: html
 134
 135    --->
 136
 137 .. toctree::
 138    :maxdepth: 1
 139    :hidden:
 140
 141     MDS States <mds-states>
 142     POSIX compatibility <posix>
 143     MDS Journaling <mds-journaling>
 144     File layouts <file-layouts>
 145     Distributed Metadata Cache <mdcache>
 146     Dynamic Metadata Management in CephFS <dynamic-metadata-management>
 147     CephFS IO Path <cephfs-io-path>
 148     LazyIO <lazyio>
 149     Directory fragmentation <dirfrags>
 150     Multiple active MDS daemons <multimds>
 151
 152
 153 .. raw:: html
 154
 155    <!---
 156
 157 Troubleshooting and Disaster Recovery
 158 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 159
 160 .. raw:: html
 161
 162    --->
 163
 164 .. toctree::
 165    :hidden:
 166
 167     Client eviction <eviction>
 168     Scrubbing the File System <scrub>
 169     Handling full file systems <full>
 170     Metadata repair <disaster-recovery-experts>
 171     Troubleshooting <troubleshooting>
 172     Disaster recovery <disaster-recovery>
 173     cephfs-journal-tool <cephfs-journal-tool>
 174     Recovering file system after monitor store loss <recover-fs-after-mon-store-loss>
 175
 176
 177 .. raw:: html
 178
 179    <!---
 180
 181 Developer Guides
 182 ^^^^^^^^^^^^^^^^
 183
 184 .. raw:: html
 185
 186    --->
 187
 188 .. toctree::
 189    :maxdepth: 1
 190    :hidden:
 191
 192     Journaler Configuration <journaler>
 193     Client's Capabilities <capabilities>
 194     Java and Python bindings <api/index>
 195     Mantle <mantle>
 196
 197
 198 .. raw:: html
 199
 200    <!---
 201
 202 Additional Details
 203 ^^^^^^^^^^^^^^^^^^
 204
 205 .. raw:: html
 206
 207    --->
 208
 209 .. toctree::
 210    :maxdepth: 1
 211    :hidden:
 212
 213     Experimental Features <experimental-features>