The volume is a block storage device we can detach, just like a USB. we can attach a volume to a single instance only. We can use the openstack client command for creating and managing volumes.  Migrating a volume-  For migrating a volume with its data from one location to another, we must have admin rights. Volume migration can be done if they are detached with no snapshots. There are some scenarios when we want to migrate the volume, such as bringing down the physical storage device for maintenance without impacting the functioning, modifying the volume properties, and freeing up space in the back end.  For migrating a volume, we can use the command-  $ openstack volume migrate [-h] --host [--force-host-copy]
[--lock-volume | --unlock-volume]
In the above example-  force-host-copy forces the host-based migration mechanism and bypasses any driver optimizations.  lock-volume | --unlock-volume applicable to the available volume for determining if other commands cause the termination of volume migration.   lock-volume locks the volume state so the migration will not get aborted in between.