At the beginning of processing, DFSMShsm obtains a list of the management classes that are active in the system, unless a volume function is processing or has just completed. See DFSMShsm retrieval of management classes and storage groups for a discussion of the exception. DFSMShsm then compares the time since each data set was last opened to the value specified with the LEVEL 1 DAYS NON-USAGE attribute in the management class with which the data set is associated. If the time since the data set was last opened is equal to or more than the value specified with the LEVEL 1 DAYS NON-USAGE attribute, the data set migrates to an ML2 volume. If either the time since the data set was last opened is less than the value specified with the LEVEL 1 DAYS NON-USAGE attribute or the attribute value is NOLIMIT, the data set migrates to another ML1 volume.
DFSMShsm does not use the TARGETLEVEL parameter to determine the migration level to which to migrate an SMS-managed data set. However, if the TARGETLEVEL parameter specifies MIGRATIONLEVEL2 with a device category, any SMS-managed data set that migrates to ML2 migrates to a device of the category specified by the MIGRATIONLEVEL2 subparameter. If the MIGRATIONLEVEL2 subparameter does not specify a device category, any SMS-managed data set that migrates to ML2 migrates to a device of the category specified by the TAPEMIGRATION parameter of the SETSYS command.