The backup function copies a data set from a level 0 volume or a level 1 migration volume to a backup volume. The result of the backup process is a backup version of the data set, which you can recover with the HRECOVER command.

The automatic backup function ensures that a current copy of new and changed data sets exists in case the original data sets are damaged or accidentally deleted. At the time and on the days specified by the storage administrator, DFSMShsm automatically copies new and changed data sets on DFSMShsm-managed volumes to tape or DASD. During automatic backup (also referred to as incremental backup), DFSMShsm backs up only new or changed data sets.

DFSMShsm automatic backup, working with SMS, uses storage group and management class attributes to determine which data sets get backed up, how often they get backed up, how many backup versions to maintain, and how long to keep those backup versions.

DFSMShsm automatic backup, working without SMS, uses the volume automatic backup attribute to backup volumes on a volume basis. The number of backup versions kept and how often they get backed up are typically the same for all non-SMS data sets in the installation, except where the HALTERDS command has been used to change specific data sets.

When you issue the HBACKDS command, the command backup function copies a specific data set to either a migration level 1 volume or to a backup tape. The data set can be cataloged or uncataloged and does not have to reside on a DASD volume that is managed by DFSMShsm. The volume, however, must be mounted.

Command backup of SMS-managed data sets is available for eligible data sets. Eligibility is controlled by an SMS management class attribute.

The inline backup function (a program called ARCINBAK) allows you to back up data sets in the middle of a job. If you use the optional TARGET keyword, ARCINBAK allows you to direct a data set to ML1 DASD or to tape.