Automatic interval migration is an option that invokes migration when DFSMShsm-managed volumes become full during high activity periods. If the storage administrator chooses this option, DFSMShsm automatically checks the level of occupancy of all DFSMShsm-managed volumes periodically. If the level of occupancy for any volume exceeds a given threshold, DFSMShsm automatically performs a subset of the space management functions on the volume. The threshold you select should be one that would be exceeded only when your installation’s activity exceeds its usual peak. For those volumes requiring interval migration, DFSMShsm can process up to 15 volume migration tasks concurrently.

During automatic interval migration on a volume, the expired data sets are deleted, then the largest eligible data sets are moved first so that the level of occupancy threshold can be reached sooner. Data sets are not migrated from ML1 to ML2 volumes during interval migration.

For system-managed volumes, DFSMShsm uses the level of occupancy thresholds established for the storage group to perform this function.

For non-system-managed volumes, DFSMShsm uses the level of occupancy thresholds established for the DFSMShsm-managed volume to perform this function.