Current design
of the aggregate backup function allows you to use the STACK parameter
on the ABACKUP command to backup only one aggregate to a minimum of
one tape. With the restriction of one aggregate backup per tape, performing
aggregate backup to a high capacity tape might leave much of the tape
empty. The aggregate stacking procedure describes how you can take
existing aggregate backup output files, and utilize MVS™ utilities to stack multiple aggregates or multiple
versions of the same aggregate onto a single tape, and then how to
recover any of the stacked aggregates from the tape. This topic includes
two sample JCL jobs, that you can use as templates to copy (stack)
a second aggregate backup onto the same tape as the first version
of the aggregate backup, and to restore an aggregate backup onto it's
original tape after a failure during the stacking procedure. You can
modify this template to stack more than two aggregates onto a tape
by duplicating the 4 steps and then modifying the data set name (ABACKUP
output file) and the LABEL number. This procedure also describes how
to:
- prevent roll-off of a backup version on the tape.
- prevent tape expiration.
- protect the stacked tape with RACF®.
- handle end of volume (EOV) error during the stacking process.
- recover backup files after an error during the stacking process.
Warning: The steps documented
in this procedure are intended to be used as an example of how to
stack multiple aggregates or multiple versions of the same aggregate
onto the same tape. This is a process that occurs outside of DFSMShsm's
knowledge and control. As DFSMShsm will not be aware that a tape may
contain multiple aggregates or multiple versions of the same aggregate,
precautions need to be taken during roll-off and EXPIREBV ABARSVERSIONS
processing to ensure that tapes are not returned to scratch that still
contain valid aggregate backups on them. See Preventing aggregate roll off and tape expiration and Deleting specific versions of aggregates from a stacked tape for a description of these precautions.