Space on a sequential-access storage volume becomes reclaimable as files expire or are deleted from the volume. Reclamation processing involves consolidating the remaining data from many sequential-access volumes onto fewer new sequential-access volumes.
Files become obsolete because of aging or limits on the number of versions of a file. Space in volumes in active-data pools also becomes reclaimable as updated files are added to the pools and as older file versions are deactivated. In reclamation processing, the server rewrites files on the volume being reclaimed to other volumes in the storage pool, making the reclaimed volume available for reuse.
The server reclaims the space in storage pools based on a reclamation threshold that you can set for each sequential-access storage pool. When the percentage of space that can be reclaimed on a volume rises above the reclamation threshold, the server reclaims the volume.