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[[storage_btrfs]]
BTRFS Backend
-------------
ifdef::wiki[]
:pve-toplevel:
:title: Storage: BTRFS
endif::wiki[]
Storage pool type: `btrfs`
On the surface, this storage type is very similar to the directory storage type,
so see the directory backend section for a general overview.
The main difference is that with this storage type `raw` formatted disks will be
placed in a subvolume, in order to allow taking snapshots and supporting offline
storage migration with snapshots being preserved.
NOTE: BTRFS will honor the `O_DIRECT` flag when opening files, meaning VMs
should not use cache mode `none`, otherwise there will be checksum errors.
Configuration
~~~~~~~~~~~~~
This backend is configured similarly to the directory storage. Note that when
adding a directory as a BTRFS storage, which is not itself also the mount point,
it is highly recommended to specify the actual mount point via the
`is_mountpoint` option.
For example, if a BTRFS file system is mounted at `/mnt/data2` and its
`pve-storage/` subdirectory (which may be a snapshot, which is recommended)
should be added as a storage pool called `data2`, you can use the following
entry:
----
btrfs: data2
path /mnt/data2/pve-storage
content rootdir,images
is_mountpoint /mnt/data2
----
Snapshots
~~~~~~~~~
When taking a snapshot of a subvolume or `raw` file, the snapshot will be
created as a read-only subvolume with the same path followed by an `@` and the
snapshot's name.
ifdef::wiki[]
See Also
~~~~~~~~
* link:/wiki/Storage[Storage]
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* link:/wiki/BTRFS[BTRFS Sysadmin]
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endif::wiki[]
