Volume considerations in a multiple DFSMShsm host environment

Consider the following when you implement DFSMShsm in a multiple DFSMShsm host environment:

DFSMShsm does not reserve the volume containing a user’s data set if the user issues a request to migrate or back up the data set, but depends upon global serialization of the SYSDSN resource.
While DFSMShsm calculates the free space of a volume, it reserves the volume. This can interfere, momentarily, with the response time for the functions that require access to that volume.
Run automatic primary space management, backup, and dump during periods of low system use and low interactive user activity to reduce contention for data sets among processors. When a DFSMShsm-managed volume is being processed by space management or backup in a DFHSMDATASETSERIALIZATION environment, other processors can have performance problems if they attempt to access the volume. To eliminate these performance problems, consider using USERDATASETSERIALIZATION instead, which will require Global Resource Serialization, or similar product, if data is shared among multiple z/OS images.
You can run automatic secondary space management (SSM) in multiple tasks. Doing so can avoid contention for SDSP data sets if you run secondary space management during primary space management. For a discussion of SDSP data set contention, see Multitasking considerations for SDSP data sets.