A management class is a list of data set migration, backup, class transition and retention attribute values. Management class also includes object expiration criteria, object backup requirements, and class transition criteria for management of objects. DFSMShsm uses the attributes of the management class associated with a data set to manage storage. When you assign a management class to a system-managed DASD data set, SMS places the management class name in both the basic catalog structure (BCS) and the VSAM volume data sets (VVDS) catalog entries of the data set. Management class is optional for system-managed data sets and does not apply to non-system-managed data sets. Management class is not used for tape data sets.
If you alter a management class definition, SMS applies the changes to any new data sets or objects after you activate the changed configuration. SMS also applies the changes to any previously allocated data sets or objects, beginning with their next scheduled management cycle (such as daily space management, backup or class transition).