INCREMENTALBACKUP: Specifying whether to back up only changed data sets during incremental volume backup

Explanation: INCREMENTALBACKUP is an optional parameter specifying whether DFSMShsm should back up only changed data sets during incremental volume backup.

Subparameter Explanation
CHANGEDONLY INCREMENTALBACKUP(CHANGEDONLY) specifies that DFSMShsm backs up the following data sets only if their change bit is on in the data set VTOC entry:
  • Non-VSAM data sets
  • VSAM data sets cataloged in an integrated catalog facility catalog.
ORIGINAL INCREMENTALBACKUP(ORIGINAL) specifies that DFSMShsm creates an initial backup version (if one does not exist) for all non-VSAM and integrated catalog facility VSAM data sets on a primary volume when incremental backup takes place, regardless of the setting of the change bit in the data set VTOC entry.

SMS relationship: Parameter differs in meaning when applied to SMS-managed or non-SMS-managed DASD volumes or data sets.

SETSYS default: If you do not specify either subparameter on any SETSYS command, the SETSYS default is ORIGINAL.

DFSMShsm default: If you do not specify this parameter on any SETSYS command, the DFSMShsm default is ORIGINAL.
Note:
  1. VSAM data sets not cataloged in an integrated catalog facility Catalog are backed up during incremental backup by comparing the date of the last update from the catalog record to the date of the last backup from the BCDS.
  2. It is suggested that you consider running the INCREMENTALBACKUP command with the ORIGINAL parameter once a month, once a quarter, or when some of the following scenarios are suspected because a backup version might not always exist for all data sets that do not have the change flag on. The scenarios are:
    • DFSMSdss or a similar product backed up the volume and reset the change flags before DFSMShsm was able to back up the data sets.
    • Users may have deleted the backup versions that DFSMShsm created and, the data sets had not been changed again.
  3. The INCREMENTALBACKUP parameter affects only data sets residing on a primary volume when incremental backup is performed. Even if you have specified ORIGINAL, no backup copy will be created for a migrated data set for which the change bit in the data set VTOC entry is off. These data sets have to be backed up individually using the BACKDS command.
Parent topic: Optional parameters of the SETSYS command