A mount request is made for the given volume in the specified library, but the volume is not currently checked into the library.
The mount operation fails. If the volume is being mounted for storage pool I/O (as opposed to import/export I/O), its ACCESS attribute is changed to UNAVAILABLE to prevent further mount requests.
Issue a CHECKIN LIBVOLUME command to return the volume into the library, and update the volumes ACCESS attribute to READONLY or READWRITE using the UPDATE VOLUME command. Retry the mount request.