How to back up custom storage volumes#

There are different ways of backing up your custom storage volumes:

Which method to choose depends both on your use case and on the storage driver you use.

In general, snapshots are quick and space efficient (depending on the storage driver), but they are stored in the same storage pool as the volume and therefore not too reliable. Export files can be stored on different disks and are therefore more reliable. They can also be used to restore a volume into a different storage pool. If you have a separate, network-connected LXD server available, regularly copying a volume to this other server gives high reliability as well, and this method can also be used to back up snapshots of the volume.

Note

Custom storage volumes might be attached to an instance, but they are not part of the instance. Therefore, the content of a custom storage volume is not stored when you back up your instance. You must back up the data of your storage volume separately.

Use snapshots for backup#

A snapshot saves the state of the storage volume at a specific time, which makes it easy to restore the volume to a previous state. It is stored in the same storage pool as the volume itself.

Most storage drivers support optimized snapshot creation (see Feature comparison). For these drivers, creating snapshots is both quick and space-efficient. For the dir driver, snapshot functionality is available but not very efficient. For the lvm driver, snapshot creation is quick, but restoring snapshots is efficient only when using thin-pool mode.

Create a snapshot of a custom storage volume#

Use the following command to create a snapshot for a custom storage volume:

lxc storage volume snapshot <pool_name> <volume_name> [<snapshot_name>]

Add the --reuse flag in combination with a snapshot name to replace an existing snapshot.

By default, snapshots are kept forever, unless the snapshots.expiry configuration option is set. To retain a specific snapshot even if a general expiry time is set, use the --no-expiry flag.

View, edit or delete snapshots#

Use the following command to display the snapshots for a storage volume:

lxc storage volume info <pool_name> <volume_name>

You can view or modify snapshots in a similar way to custom storage volumes, by referring to the snapshot with <volume_name>/<snapshot_name>.

To show information about a snapshot, use the following command:

lxc storage volume show <pool_name> <volume_name>/<snapshot_name>

To edit a snapshot (for example, to add a description or change the expiry date), use the following command:

lxc storage volume edit <pool_name> <volume_name>/<snapshot_name>

To delete a snapshot, use the following command:

lxc storage volume delete <pool_name> <volume_name>/<snapshot_name>

Schedule snapshots of a custom storage volume#

You can configure a custom storage volume to automatically create snapshots at specific times. To do so, set the snapshots.schedule configuration option for the storage volume (see Configure storage volume settings).

For example, to configure daily snapshots, use the following command:

lxc storage volume set <pool_name> <volume_name> snapshots.schedule @daily

To configure taking a snapshot every day at 6 am, use the following command:

lxc storage volume set <pool_name> <volume_name> snapshots.schedule "0 6 * * *"

When scheduling regular snapshots, consider setting an automatic expiry (snapshots.expiry) and a naming pattern for snapshots (snapshots.pattern). See the Storage drivers documentation for more information about those configuration options.

Restore a snapshot of a custom storage volume#

You can restore a custom storage volume to the state of any of its snapshots.

To do so, you must first stop all instances that use the storage volume. Then use the following command:

lxc storage volume restore <pool_name> <volume_name> <snapshot_name>

You can also restore a snapshot into a new custom storage volume, either in the same storage pool or in a different one (even a remote storage pool). To do so, use the following command:

lxc storage volume copy <source_pool_name>/<source_volume_name>/<source_snapshot_name> <target_pool_name>/<target_volume_name>

Use export files for backup#

You can export the full content of your custom storage volume to a standalone file that can be stored at any location. For highest reliability, store the backup file on a different file system to ensure that it does not get lost or corrupted.

Export a custom storage volume#

Use the following command to export a custom storage volume to a compressed file (for example, /path/to/my-backup.tgz):

lxc storage volume export <pool_name> <volume_name> [<file_path>]

If you do not specify a file path, the export file is saved as backup.tar.gz in the working directory.

Warning

If the output file (backup.tar.gz or the specified file path) already exists, the command overwrites the existing file without warning.

You can add any of the following flags to the command:

--compression

By default, the output file uses gzip compression. You can specify a different compression algorithm (for example, bzip2) or turn off compression with --compression=none.

--optimized-storage

If your storage pool uses the btrfs or the zfs driver, add the --optimized-storage flag to store the data as a driver-specific binary blob instead of an archive of individual files. In this case, the export file can only be used with pools that use the same storage driver.

Exporting a volume in optimized mode is usually quicker than exporting the individual files. Snapshots are exported as differences from the main volume, which decreases their size and makes them easily accessible.

--volume-only

By default, the export file contains all snapshots of the storage volume. Add this flag to export the volume without its snapshots.

Restore a custom storage volume from an export file#

You can import an export file (for example, /path/to/my-backup.tgz) as a new custom storage volume. To do so, use the following command:

lxc storage volume import <pool_name> <file_path> [<volume_name>]

If you do not specify a volume name, the original name of the exported storage volume is used for the new volume. If a volume with that name already (or still) exists in the specified storage pool, the command returns an error. In that case, either delete the existing volume before importing the backup or specify a different volume name for the import.