When you run multiple tasks in a multiple DFSMShsm host configuration, consider the most effective use of your z/OS image and the number of DFSMShsm hosts running within each of those z/OS images. For example, you might ask whether it is more efficient to perform eight tasks with one z/OS image or four tasks with two z/OS images. The answer is that, for space management and backup, it is generally better to perform eight tasks with one z/OS image and distribute those tasks across multiple hosts running in that z/OS image. The reason that one z/OS image offers better performance than two is a result of the DFSMShsm CDS sharing protocol.

For performance reasons, run several migration or backup tasks in one z/OS image versus running a few tasks in each of multiple host environment; however for CDSSHR=RLS, it is better to spread out the tasking across multiple DFSMShsms.