Migration to a DASD level 2 volume

For each data set that migrates from an ML1 volume to DASD ML2, DFSMShsm uses the set of initial characters of the data set name and the key ranges that you defined to choose the DASD ML2 volume. The key range is the total set of data set names whose initial characters are between a low key and a high key in collating sequence.

If DFSMShsm fails the migration of data sets from an ML1 volume to an ML2 volume because the ML2 volume being used with that key range does not have enough space, DFSMShsm does the following:

1. Disassociates the full volume from the key range.
2. Tries to assign an available DASD ML2 volume to the key range in place of the full volume. An available DASD ML2 volume is a volume that meets all of the following criteria:
   • It has been added to DFSMShsm as an ML2 volume. The ADDVOL volid MIGRATION(MIGRATIONLEVEL2) command adds ML2 volumes to DFSMShsm.
   • It has not been associated with a key range. The DEFINE MIGRATIONLEVEL2(KEYS(key . . .) VOLUMES(volid . . .)) command associates ML2 volumes with key ranges.
   • DFSMShsm has never chosen it as a replacement for an ML2 volume.
   • It does not have the DRAIN attribute in its ADDVOL command.
3. Retries the migration of the data set one time.

If there is no ML2 volume to choose as a replacement volume, DFSMShsm stops level 1 to level 2 migration for the key range defined for the full ML2 volume. DFSMShsm continues migrating data sets for all other key ranges.