Reclaiming copy storage pools and active-data pools

Reclamation of volumes in copy storage pools and active-data pools is similar to reclamation in primary storage pools. For volumes that are on-site, reclamation usually occurs after the volume is full and then begins to empty because of file deletion, expiration, or, in the case of active-data pools, deactivation. When the percentage of reclaimable space on a volume rises above the reclamation threshold, the server reclaims the volume. Active files on the volume are rewritten to other volumes in the storage pool, making the original volume available for new files.

For off-site volumes, reclamation can occur when the percentage of unused space on the volume is greater than the reclaim parameter value. The unused space in copy storage pool volumes includes both space that has never been used on the volume and space that has become empty because of file deletion or expiration. For volumes in active-data pools, reclaimable space also includes inactive versions of files. Most volumes in copy storage pools and active-data pools might be set to an access mode of off-site, making them ineligible to be mounted. During reclamation, the server copies valid files on off-site volumes from the original files in the primary storage pools. In this way, the server copies valid files on off-site volumes without having to mount these volumes. For more information, see Reclamation of offsite volumes.

Reclamation of copy storage pool volumes and active-data pool volumes should be done periodically to allow the reuse of partially filled volumes that are off-site. Reclamation can be done automatically by setting the reclamation threshold for the copy storage pool or the active-data pool to less than 100%. However, you need to consider controlling when reclamation occurs because of how off-site volumes are treated. For more information, see Controlling when reclamation occurs for off-site volumes.

Tip: You can reclaim space in off-site volumes controlled by a z/OS® media server.

Using the RECLAIMPROCESS parameter on the DEFINE STGPOOL or UPDATE STGPOOL command, you can specify multiple concurrent reclamation processes for a single copy storage pool or active-data pool. Doing so will let you make better use of your available tape drives or FILE volumes. The principles underlying multiple concurrent reclamation processes for copy storage pools and active-data pools are the same principles as those for primary sequential-access storage pools. In particular, you need to carefully consider available resources (for example, the number of mount points) when calculating how many processes you can run concurrently. For details, see Optimizing drive usage using multiple concurrent reclamation processes.

Reclamation of primary storage pool volumes does not affect copy storage pool files or files in active-data pools.