pve-storage-btrfs.adoc

   1 [[storage_btrfs]]
   2 BTRFS Backend
   3 -------------
   4 ifdef::wiki[]
   5 :pve-toplevel:
   6 :title: Storage: BTRFS
   7 endif::wiki[]
   8
   9 Storage pool type: `btrfs`
  10
  11 On the surface, this storage type is very similar to the directory storage type,
  12 so see the directory backend section for a general overview.
  13
  14 The main difference is that with this storage type `raw` formatted disks will be
  15 placed in a subvolume, in order to allow taking snapshots and supporting offline
  16 storage migration with snapshots being preserved.
  17
  18 NOTE: BTRFS will honor the `O_DIRECT` flag when opening files, meaning VMs
  19 should not use cache mode `none`, otherwise there will be checksum errors.
  20
  21 Configuration
  22 ~~~~~~~~~~~~~
  23
  24 This backend is configured similarly to the directory storage. Note that when
  25 adding a directory as a BTRFS storage, which is not itself also the mount point,
  26 it is highly recommended to specify the actual mount point via the
  27 `is_mountpoint` option.
  28
  29 For example, if a BTRFS file system is mounted at `/mnt/data2` and its
  30 `pve-storage/` subdirectory (which may be a snapshot, which is recommended)
  31 should be added as a storage pool called `data2`, you can use the following
  32 entry:
  33
  34 ----
  35 btrfs: data2
  36         path /mnt/data2/pve-storage
  37         content rootdir,images
  38         is_mountpoint /mnt/data2
  39 ----
  40
  41 Snapshots
  42 ~~~~~~~~~
  43
  44 When taking a snapshot of a subvolume or `raw` file, the snapshot will be
  45 created as a read-only subvolume with the same path followed by an `@` and the
  46 snapshot's name.
  47
  48 ifdef::wiki[]
  49
  50 See Also
  51 ~~~~~~~~
  52
  53 * link:/wiki/Storage[Storage]
  54 * link:/wiki/BTRFS[BTRFS Sysadmin]
  55
  56 endif::wiki[]