Automatic backup processing

Assume that it is 3 a.m. in the morning. Because this is a Monday, it is a Y day in the backup cycle. The combination of the Y day in the backup cycle, the BACKUP parameter of the SETSYS command, and the AUTOBACKUPSTART parameter of the SETSYS command cause automatic backup to start in host 1.

Automatic backup is performed in four phases:

  1. Backing up the control data sets
  2. Moving backup versions
  3. Backing up migrated data sets
  4. Backing up DFSMShsm-managed volumes

In multiple DFSMShsm-host configurations, only the primary host performs the first three phases. The first three phases are performed as successive phases of a single task.

If the primary host fails in a multiple DFSMShsm-host environment where the secondary host promotion function is being used, the promoted host can take over the first three phases for the failed primary host.

At the beginning of backup in each of the hosts, DFSMShsm requests a list of all defined management classes. If SMS does not return the list, DFSMShsm considers SMS inactive and issues a message that backup cannot be performed for SMS-managed volumes. If SMS is active, DFSMShsm obtains a list of the volumes associated with storage groups that the host is allowed to process, and that have the following characteristics: the AUTO BACKUP ===> Y attribute, are type POOL, and have a status of ENABLED, QUIESCED NEW, or DISABLED NEW. Volumes in storage groups that have a host specified by the BACKUP SYSTEM/SYSPLEX NAME have a host affinity. If SMS is not installed and active, DFSMShsm processes only non-SMS-managed DASD volumes. For purposes of the illustration, it is assumed that SMS is installed and active.

DFSMShsm selects the following order of processing as a method of controlling input path contention, subject to prioritization for SMS volumes restricted to processing by one host:

  1. Affinity SMS volumes
  2. Retry of in-use affinity SMS volumes
  3. Non-SMS and nonaffinity SMS volumes

After DFSMShsm has attempted to process all candidate volumes eligible for automatic backup, DFSMShsm retries the selection of any of these volumes found in-use by another DFSMShsm function.

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