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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[]