Specifying the maximum number of dump tasks

DFSMShsm can run up to 64 dump tasks concurrently in each host. Because DFSMShsm can make up to five dump copies concurrently for each dump task, the number of dump tasks does not limit the number of dump copies. In deciding how many dump tasks to specify, consider how many tape units are available to receive the dump copies.

The MAXDUMPTASKS parameter of the SETSYS command controls how many dump tasks run concurrently. In the example system the use of three concurrent dump tasks is demonstrated. The following SETSYS command is added to the ARCCMDxx member in each host in the example system:

SETSYS MAXDUMPTASKS(3)

Because it has been specified that each storage group have two dump classes, six tape units must be available for each host on the days when both dump classes are scheduled.

If any dump class involved specifies a STACK value of more than one, DFSMShsm writes multiple dump copies sequentially as each tape is mounted for that dump class. That can reduce the number of tape drives (the number of dump tasks) needed concurrently, but the reduced parallelism can lengthen the total time needed for the automatic dump window specified by SETSYS AUTODUMPSTART.