Specifying when to migrate from ML1 to ML2

If you back up or migrate data sets to ML1 OVERFLOW volumes (see Specifying migration of data sets to overflow volumes), you can specify the percentage of occupied space that must be in the ML1 OVERFLOW volume pool before the migration of data sets to ML2 volumes occurs during automatic secondary space management.

As shown in the example below, the default setting for the ML1 OVERFLOW volume pool threshold is 80%. This requires the occupied space of the entire overflow volume pool reach 80% full before any data is moved off of OVERFLOW volumes to ML2 volumes.

SETSYS ML1OVERFLOW(THRESHOLD(80))

In this case, the percentage of occupied space for each ML1 OVERFLOW volume will be calculated and then DFSMShsm will compare the average value with the specified threshold (80%). If the average of the ML1 OVERFLOW volume pool has an occupancy that is equal to or greater than the threshold, then secondary space management will be started and move data from ML1 to ML2. See ML1OVERFLOW: Manage ML1 OVERFLOW volumes.