To use the DEFRAG command to relocate data extents on a DASD volume, you need DASDVOL-access authority to that volume or READ-access to the data sets that are relocated. Otherwise, only unprotected data sets are relocated.

As part of the DEFRAG operation, DFSMSdss creates a work data set (SYS1.DFDSS.DEFRAG.xxxxxxxx.volser.DUMMY), which is deleted after successful completion of the DEFRAG function. If the DEFRAG operation is prematurely ended, rerun the DEFRAG function to clean up this data set.