During a database backup or restore operation, a required volume cannot be mounted, because the mount request was canceled.
If the database backup was started with the BACKUP DB command, the database backup is ended and server operation continues. If the database backup was triggered automatically, the backup stops and the server waits for the retry period to expire and then tries the database backup again. A database restore is terminated.
Issue the command again or wait for the server to retry the backup and make sure the necessary volumes are accessible. If you are restoring a database to a given date or doing a roll-forward restore, restart the entire restore operation. If you are restoring a single database backup with COMMIT=NO, reissue the restore command. If you are restoring a database backup with COMMIT=YES, restore the complete backup series from the beginning.