Backing up an individual data set

You can use one of the following data set backup commands to back up a single data set:

   BACKDS dsname

   HBACKDS dsname|dsn_filter_name

Note: You can also use the ARCINBAK program and the ARCHBACK macro to submit data set backup requests. DFSMShsm processes these requests according to descriptions in this topic.

In processing these commands, DFSMShsm first checks the management class for the data set to determine the value of the ADMIN OR USER COMMAND BACKUP attribute. If the value of the attribute is BOTH, a DFSMShsm-authorized user can use either of the commands, and a non-DFSMShsm-authorized user can use the HBACKDS command to back up the data set. If the value of the attribute is ADMIN, a DFSMShsm-authorized user can use either of the commands to back up the data set, but a non-DFSMShsm-authorized user cannot back up the data set. If the value of the attribute is NONE, the command backup cannot be done.

The following process occurs when an individual data set is backed up to DASD:

  1. DFSMShsm can create backup copies to either ML1 backup OVERFLOW volumes or NOOVERFLOW volumes. Use the SETSYS ML1OVERFLOW(DATASETSIZE(dssize)) command to specify the minimum size in K bytes (where K=1024) of the data set for which an ML1 OVERFLOW volume is preferred for the migration or backup copy.

    For data sets smaller than 58K tracks, DFSMShsm allocates a basic sequential format data set for the backup copy.

    For data sets larger than 58K tracks, DFSMShsm allocates a large format sequential data set for the backup copy. Basic or large format sequential data sets will prefer OVERFLOW or NOOVERFLOW volumes based on the SETSYS ML1OVERFLOW(DATASETSIZE(dssize)) value. If there is not enough free space on the NOOVERFLOW or OVERFLOW volume for a particular backup copy, DFSMShsm tries to create the backup on a OVERFLOW or NOOVERFLOW volume respectively. If the data set is too large to fit on a single ML1 volume (OVERFLOW or NOOVERFLOW), then the migration or backup fails.

  2. Build an MCM record in the BCDS to indicate that the backup copy must be moved to a backup volume.
  3. Set the data-set-changed indicator to off and update the last backup date fields in the catalog entry and the BCDS MCB record.
  4. Invalidate the oldest versions if the number of backup versions exceeds the value specified by the NUMBER OF BACKUPS (DATA SET EXISTS) management class attribute.

If the backup to DASD is unsuccessful, a message is issued.

The following process occurs when an individual data set is backed up to tape:

  1. Copy the data set to a backup tape volume.
  2. Set the data-set-changed indicator to off and update the last backup date fields in the catalog entry and the BCDS MCB record.
  3. Invalidate the oldest versions if the number of backup versions exceeds the value specified by the NUMBER OF BACKUPS (DATA SET EXISTS) management class attribute.

If the backup to tape is unsuccessful, a message is issued.

DFSMShsm does not back up an SMS-managed data set if SMS is not installed and active in the system.

Parent topic: Command availability management