Storage pools, volumes, and data movement
This domain tests storage design and data movement. Primary storage pools receive backup and archive data; copy pools hold duplicate copies; active-data pools hold only active versions. Volumes are the physical or logical units behind pools, and device classes describe the storage technology.
Core rules
Define a device class, then a storage pool, then volumes. Disk pools are often used as landing pools and migrated to tape or container pools. MIGRATE STGPOOL moves files from a pool to the next pool in the hierarchy. BACKUP STGPOOL creates a copy pool copy. RECLAIM STGPOOL rewrites remaining files from fragmented volumes so volumes can be reused. MAXSCRATCH limits scratch volumes a pool may consume. Collocation controls how client data is distributed across volumes.
Worked example
Define DISKPOOL with file volumes, then TAPEPOOL with a tape device class and MAXSCRATCH=50. Set DISKPOOL to migrate to TAPEPOOL when it reaches a high threshold, and define TAPECOPY as a copy pool. Run BACKUP STGPOOL TAPEPOOL TAPECOPY after migration. The reasoning is: primary pool receives backups, migration moves data onward, and backup stgpool creates a second copy for recovery.
Traps
Do not send client backups directly to a copy pool. Do not confuse migration with expiration; migration moves data, while expiration deletes eligible versions. Reclamation needs free space or scratch volumes. A pool without sufficient scratch can stall migration or backup. Active-data pools are not general backup targets.