The first phase of automatic backup can include the backup of DFSMShsm control data sets on the primary processor. Exclusive serialization ensures that the CDSs are not changed while DFSMShsm is backing them up. After they have been backed up, exclusive serialization is changed to shared serialization. Because the automatic primary space management, automatic secondary space management, and automatic dump processes can change records, they do shared serialization on the control data sets.

During automatic volume processing, DFSMShsm skips over a DFSMShsm-managed volume currently being processed anywhere in the configuration sharing the DFSMShsm control data sets. DFSMShsm then retries those skipped DFSMShsm-managed volumes after processing the rest of the volumes. DFSMShsm tries processing the skipped volumes up to nine times. DFSMShsm waits for five minutes between volume process attempts if it does not process any skipped volumes during the retry loop through the list. If a volume is not processed, an error message is written to the function’s activity log.

Commands that cause changes to control data sets do not run while the control data sets are being backed up and are suspended until the control data set backup completes.