Data sets managed by Storage Management Subsystem

If you have the Storage Management Subsystem (SMS) active, you can move tape data sets to Direct Access Storage Device (DASD) to take advantage of the space, performance, and availability capabilities of SMS. If you put these tape data sets on DASD, you will have less tape activity, use fewer tapes, and need less operator intervention. DFSMShsm can move large numbers of appropriate data sets to tape much more efficiently than if users controlled it directly.

For more information about SMS, see z/OS DFSMS Introduction. Also, z/OS DFSMSdfp Storage Administration explains how to move tape data sets to DASD.