As DFSMShsm uses a tape volume, DFSMSrmm records information about data sets and multivolume data sets at OPEN time. DFSMSrmm can use this information to manage the volumes based on the DFSMSrmm policies you define.

DFSMShsm uses the DCB Open/EOV volume security and verification exit to ensure that an acceptable volume is mounted for DFSMShsm's use. DFSMShsm uses this exit to reject unacceptable volumes. For example, DFSMShsm rejects volumes already in use by DFSMShsm and volumes that are not authorized for use by DFSMShsm. DFSMSrmm records information only for those volumes not rejected by DFSMShsm.

DFSMSrmm provides facilities so that DFSMShsm can tell DFSMSrmm when it no longer requires a tape volume or when a tape volume changes status. The benefit is that DFSMShsm cannot mistakenly overwrite one of its own tape volumes if an operator mounts a tape volume in response to a request for a non-specific tape volume.