If a file system is unmounted and remains so for a predetermined time, the system can migrate it to a lower priority storage medium. The system automatically recalls a migrated file system from migration storage if a mount command is issued for the file system.

If you plan to migrate HFS data sets, consider migrating them only to level 1 (DASD) storage. Recalling a data set that was migrated to tape could adversely affect performance because of the time required to physically mount the tape volume.

If the tape is in an automated library, then recalling it should be much faster than if the system has to request an operator to mount it.