A volume backup can only be restored on the same Block Storage
service. This is because restoring a volume from a backup requires
metadata available on the database used by the Block Storage
service.

You can, however, export the metadata of a volume backup. To do so,
run this command as an OpenStack admin user (presumably,
after creating a volume backup):

$ cinder backup-export BACKUP_ID

Where BACKUP_ID is the volume backup’s ID. This command
should return the backup’s corresponding database information as encoded
string metadata.

Exporting and storing this encoded string metadata allows you to
completely restore the backup, even in the event of a catastrophic
database failure. This will preclude the need to back up the entire
Block Storage database, particularly if you only need to keep complete
backups of a small subset of volumes.

If you have placed encryption on your volumes, the encryption will
still be in place when you restore the volume if a UUID encryption key
is specified when creating volumes. Using backup metadata support, UUID
keys set up for a volume (or volumes) will remain valid when you restore
a backed-up volume. The restored volume will remain encrypted, and will
be accessible with your credentials.

In addition, having a volume backup and its backup metadata also
provides volume portability. Specifically, backing up a volume and
exporting its metadata will allow you to restore the volume on a
completely different Block Storage database, or even on a different
cloud service. To do so, first import the backup metadata to the Block
Storage database and then restore the backup.

To import backup metadata, run the following command as an OpenStack
admin:

$ cinder backup-import METADATA

Where METADATA is the backup metadata exported
earlier.

Once you have imported the backup metadata into a Block Storage
database, restore the volume (see the section called volume_backups).