ceph/doc/cephfs/fs-volumes.rst

   1 .. _fs-volumes-and-subvolumes:
   2
   3 FS volumes and subvolumes
   4 =========================
   5
   6 A  single source of truth for CephFS exports is implemented in the volumes
   7 module of the :term:`Ceph Manager` daemon (ceph-mgr). The OpenStack shared
   8 file system service (manila_), Ceph Container Storage Interface (CSI_),
   9 storage administrators among others can use the common CLI provided by the
  10 ceph-mgr volumes module to manage the CephFS exports.
  11
  12 The ceph-mgr volumes module implements the following file system export
  13 abstactions:
  14
  15 * FS volumes, an abstraction for CephFS file systems
  16
  17 * FS subvolumes, an abstraction for independent CephFS directory trees
  18
  19 * FS subvolume groups, an abstraction for a directory level higher than FS
  20   subvolumes to effect policies (e.g., :doc:`/cephfs/file-layouts`) across a
  21   set of subvolumes
  22
  23 Some possible use-cases for the export abstractions:
  24
  25 * FS subvolumes used as manila shares or CSI volumes
  26
  27 * FS subvolume groups used as manila share groups
  28
  29 Requirements
  30 ------------
  31
  32 * Nautilus (14.2.x) or a later version of Ceph
  33
  34 * Cephx client user (see :doc:`/rados/operations/user-management`) with
  35   the following minimum capabilities::
  36
  37     mon 'allow r'
  38     mgr 'allow rw'
  39
  40
  41 FS Volumes
  42 ----------
  43
  44 Create a volume using::
  45
  46     $ ceph fs volume create <vol_name> [<placement>]
  47
  48 This creates a CephFS file system and its data and metadata pools. It also tries
  49 to create MDSes for the filesystem using the enabled ceph-mgr orchestrator
  50 module  (see :doc:`/mgr/orchestrator`) , e.g., rook.
  51
  52 Remove a volume using::
  53
  54     $ ceph fs volume rm <vol_name> [--yes-i-really-mean-it]
  55
  56 This removes a file system and its data and metadata pools. It also tries to
  57 remove MDSes using the enabled ceph-mgr orchestrator module.
  58
  59 List volumes using::
  60
  61     $ ceph fs volume ls
  62
  63 FS Subvolume groups
  64 -------------------
  65
  66 Create a subvolume group using::
  67
  68     $ ceph fs subvolumegroup create <vol_name> <group_name> [--pool_layout <data_pool_name> --uid <uid> --gid <gid> --mode <octal_mode>]
  69
  70 The command succeeds even if the subvolume group already exists.
  71
  72 When creating a subvolume group you can specify its data pool layout (see
  73 :doc:`/cephfs/file-layouts`), uid, gid, and file mode in octal numerals. By default, the
  74 subvolume group is created with an octal file mode '755', uid '0', gid '0' and data pool
  75 layout of its parent directory.
  76
  77
  78 Remove a subvolume group using::
  79
  80     $ ceph fs subvolumegroup rm <vol_name> <group_name> [--force]
  81
  82 The removal of a subvolume group fails if it is not empty or non-existent.
  83 '--force' flag allows the non-existent subvolume group remove command to succeed.
  84
  85
  86 Fetch the absolute path of a subvolume group using::
  87
  88     $ ceph fs subvolumegroup getpath <vol_name> <group_name>
  89
  90 List subvolume groups using::
  91
  92     $ ceph fs subvolumegroup ls <vol_name>
  93
  94 Create a snapshot (see :doc:`/cephfs/experimental-features`) of a
  95 subvolume group using::
  96
  97     $ ceph fs subvolumegroup snapshot create <vol_name> <group_name> <snap_name>
  98
  99 This implicitly snapshots all the subvolumes under the subvolume group.
 100
 101 Remove a snapshot of a subvolume group using::
 102
 103     $ ceph fs subvolumegroup snapshot rm <vol_name> <group_name> <snap_name> [--force]
 104
 105 Using the '--force' flag allows the command to succeed that would otherwise
 106 fail if the snapshot did not exist.
 107
 108 List snapshots of a subvolume group using::
 109
 110     $ ceph fs subvolumegroup snapshot ls <vol_name> <group_name>
 111
 112
 113 FS Subvolumes
 114 -------------
 115
 116 Create a subvolume using::
 117
 118     $ ceph fs subvolume create <vol_name> <subvol_name> [--size <size_in_bytes> --group_name <subvol_group_name> --pool_layout <data_pool_name> --uid <uid> --gid <gid> --mode <octal_mode> --namespace-isolated]
 119
 120
 121 The command succeeds even if the subvolume already exists.
 122
 123 When creating a subvolume you can specify its subvolume group, data pool layout,
 124 uid, gid, file mode in octal numerals, and size in bytes. The size of the subvolume is
 125 specified by setting a quota on it (see :doc:`/cephfs/quota`). The subvolume can be
 126 created in a separate RADOS namespace by specifying --namespace-isolated option. By
 127 default a subvolume is created within the default subvolume group, and with an octal file
 128 mode '755', uid of its subvolume group, gid of its subvolume group, data pool layout of
 129 its parent directory and no size limit.
 130
 131 Remove a subvolume using::
 132
 133     $ ceph fs subvolume rm <vol_name> <subvol_name> [--group_name <subvol_group_name> --force]
 134
 135
 136 The command removes the subvolume and its contents. It does this in two steps.
 137 First, it move the subvolume to a trash folder, and then asynchronously purges
 138 its contents.
 139
 140 The removal of a subvolume fails if it has snapshots, or is non-existent.
 141 '--force' flag allows the non-existent subvolume remove command to succeed.
 142
 143 Resize a subvolume using::
 144
 145     $ ceph fs subvolume resize <vol_name> <subvol_name> <new_size> [--group_name <subvol_group_name>] [--no_shrink]
 146
 147 The command resizes the subvolume quota using the size specified by 'new_size'.
 148 '--no_shrink' flag prevents the subvolume to shrink below the current used size of the subvolume.
 149
 150 The subvolume can be resized to an infinite size by passing 'inf' or 'infinite' as the new_size.
 151
 152 Fetch the absolute path of a subvolume using::
 153
 154     $ ceph fs subvolume getpath <vol_name> <subvol_name> [--group_name <subvol_group_name>]
 155
 156 Fetch the metadata of a subvolume using::
 157
 158     $ ceph fs subvolume info <vol_name> <subvol_name> [--group_name <subvol_group_name>]
 159
 160 The output format is json and contains fields as follows.
 161
 162 * atime: access time of subvolume path in the format "YYYY-MM-DD HH:MM:SS"
 163 * mtime: modification time of subvolume path in the format "YYYY-MM-DD HH:MM:SS"
 164 * ctime: change time of subvolume path in the format "YYYY-MM-DD HH:MM:SS"
 165 * uid: uid of subvolume path
 166 * gid: gid of subvolume path
 167 * mode: mode of subvolume path
 168 * mon_addrs: list of monitor addresses
 169 * bytes_pcent: quota used in percentage if quota is set, else displays "undefined"
 170 * bytes_quota: quota size in bytes if quota is set, else displays "infinite"
 171 * bytes_used: current used size of the subvolume in bytes
 172 * created_at: time of creation of subvolume in the format "YYYY-MM-DD HH:MM:SS"
 173 * data_pool: data pool the subvolume belongs to
 174 * path: absolute path of a subvolume
 175 * type: subvolume type indicating whether it's clone or subvolume
 176 * pool_namespace: RADOS namespace of the subvolume
 177
 178 List subvolumes using::
 179
 180     $ ceph fs subvolume ls <vol_name> [--group_name <subvol_group_name>]
 181
 182 Create a snapshot of a subvolume using::
 183
 184     $ ceph fs subvolume snapshot create <vol_name> <subvol_name> <snap_name> [--group_name <subvol_group_name>]
 185
 186
 187 Remove a snapshot of a subvolume using::
 188
 189     $ ceph fs subvolume snapshot rm <vol_name> <subvol_name> <snap_name> [--group_name <subvol_group_name> --force]
 190
 191 Using the '--force' flag allows the command to succeed that would otherwise
 192 fail if the snapshot did not exist.
 193
 194 List snapshots of a subvolume using::
 195
 196     $ ceph fs subvolume snapshot ls <vol_name> <subvol_name> [--group_name <subvol_group_name>]
 197
 198 Fetch the metadata of a snapshot using::
 199
 200     $ ceph fs subvolume snapshot info <vol_name> <subvol_name> <snap_name> [--group_name <subvol_group_name>]
 201
 202 The output format is json and contains fields as follows.
 203
 204 * created_at: time of creation of snapshot in the format "YYYY-MM-DD HH:MM:SS:ffffff"
 205 * data_pool: data pool the snapshot belongs to
 206 * has_pending_clones: "yes" if snapshot clone is in progress otherwise "no"
 207 * protected: "yes" if snapshot is protected otherwise "no"
 208 * size: snapshot size in bytes
 209
 210 Cloning Snapshots
 211 -----------------
 212
 213 Subvolumes can be created by cloning subvolume snapshots. Cloning is an asynchronous operation involving copying
 214 data from a snapshot to a subvolume. Due to this bulk copy nature, cloning is currently inefficient for very huge
 215 data sets.
 216
 217 Before starting a clone operation, the snapshot should be protected. Protecting a snapshot ensures that the snapshot
 218 cannot be deleted when a clone operation is in progress. Snapshots can be protected using::
 219
 220   $ ceph fs subvolume snapshot protect <vol_name> <subvol_name> <snap_name> [--group_name <subvol_group_name>]
 221
 222 To initiate a clone operation use::
 223
 224   $ ceph fs subvolume snapshot clone <vol_name> <subvol_name> <snap_name> <target_subvol_name>
 225
 226 If a snapshot (source subvolume) is a part of non-default group, the group name needs to be specified as per::
 227
 228   $ ceph fs subvolume snapshot clone <vol_name> <subvol_name> <snap_name> <target_subvol_name> --group_name <subvol_group_name>
 229
 230 Cloned subvolumes can be a part of a different group than the source snapshot (by default, cloned subvolumes are created in default group). To clone to a particular group use::
 231
 232   $ ceph fs subvolume snapshot clone <vol_name> <subvol_name> <snap_name> <target_subvol_name> --target_group_name <subvol_group_name>
 233
 234 Similar to specifying a pool layout when creating a subvolume, pool layout can be specified when creating a cloned subvolume. To create a cloned subvolume with a specific pool layout use::
 235
 236   $ ceph fs subvolume snapshot clone <vol_name> <subvol_name> <snap_name> <target_subvol_name> --pool_layout <pool_layout>
 237
 238 To check the status of a clone operation use::
 239
 240   $ ceph fs clone status <vol_name> <clone_name> [--group_name <group_name>]
 241
 242 A clone can be in one of the following states:
 243
 244 #. `pending`     : Clone operation has not started
 245 #. `in-progress` : Clone operation is in progress
 246 #. `complete`    : Clone operation has sucessfully finished
 247 #. `failed`      : Clone operation has failed
 248
 249 Sample output from an `in-progress` clone operation::
 250
 251   $ ceph fs subvolume snapshot protect cephfs subvol1 snap1
 252   $ ceph fs subvolume snapshot clone cephfs subvol1 snap1 clone1
 253   $ ceph fs clone status cephfs clone1
 254   {
 255     "status": {
 256       "state": "in-progress",
 257       "source": {
 258         "volume": "cephfs",
 259         "subvolume": "subvol1",
 260         "snapshot": "snap1"
 261       }
 262     }
 263   }
 264
 265 (NOTE: since `subvol1` is in default group, `source` section in `clone status` does not include group name)
 266
 267 .. note:: Cloned subvolumes are accessible only after the clone operation has successfully completed.
 268
 269 For a successsful clone operation, `clone status` would look like so::
 270
 271   $ ceph fs clone status cephfs clone1
 272   {
 273     "status": {
 274       "state": "complete"
 275     }
 276   }
 277
 278 or `failed` state when clone is unsuccessful.
 279
 280 On failure of a clone operation, the partial clone needs to be deleted and the clone operation needs to be retriggered.
 281 To delete a partial clone use::
 282
 283   $ ceph fs subvolume rm <vol_name> <clone_name> [--group_name <group_name>] --force
 284
 285 When no clone operations are in progress or scheduled, the snaphot can be unprotected. To unprotect a snapshot use::
 286
 287   $ ceph fs subvolume snapshot unprotect <vol_name> <subvol_name> <snap_name> [--group_name <subvol_group_name>]
 288
 289 Note that unprotecting a snapshot would fail if there are pending or in progress clone operations. Also note that,
 290 only unprotected snapshots can be removed. This guarantees that a snapshot cannot be deleted when clones are pending
 291 (or in progress).
 292
 293 .. note:: Cloning only synchronizes directories, regular files and symbolic links. Also, inode timestamps (access and
 294           modification times) are synchronized upto seconds granularity.
 295
 296 An `in-progress` or a `pending` clone operation can be canceled. To cancel a clone operation use the `clone cancel` command::
 297
 298   $ ceph fs clone cancel <vol_name> <clone_name> [--group_name <group_name>]
 299
 300 On successful cancelation, the cloned subvolume is moved to `canceled` state::
 301
 302   $ ceph fs subvolume snapshot protect cephfs subvol1 snap1
 303   $ ceph fs subvolume snapshot clone cephfs subvol1 snap1 clone1
 304   $ ceph fs clone cancel cephfs clone1
 305   $ ceph fs clone status cephfs clone1
 306   {
 307     "status": {
 308       "state": "canceled",
 309       "source": {
 310         "volume": "cephfs",
 311         "subvolume": "subvol1",
 312         "snapshot": "snap1"
 313       }
 314     }
 315   }
 316
 317 .. note:: The canceled cloned can be deleted by using --force option in `fs subvolume rm` command.
 318
 319 .. _manila: https://github.com/openstack/manila
 320 .. _CSI: https://github.com/ceph/ceph-csi