Explanation: STORAGEGROUP(sgn,...)
is a required parameter specifying that DFSMShsm backs up the eligible
data sets on the volumes in one or more storage groups or it dumps
the volumes in one or more storage groups. For sgn, substitute
the names of the storage groups that DFSMShsm processes. (A storage
group name appearing more than once in the list is backed up or dumped
only once.)
If you specify DUMP, DFSMShsm concurrently targets dump copies
to one or more dump classes (specified in the command or associated
with the storage groups). If stacking is specified (in the command
or in the dump class definitions), DFSMShsm uses its dump stacking
process to stack multiple dump copies on dump volumes. Specifying
DUMPCLASS means that DFSMShsm dumps all storage groups specified to
the same set of specified dump classes.
Defaults: None.
Note: - A message is issued, and the backup or dump is not processed if
DFSMShsm is running in a non-SMS environment.
- A message is issued and the backup or dump will not be processed
for any volumes which are in initial status or can not be determined
to be SMS-managed volumes.
- If you specify STORAGEGROUP without sgn, the command
fails. If you specify STORAGEGROUP with more than 30 storage groups,
only the first 30 are processed.
- If you specify DUMP with DUMPCLASS, and at least one of the dump
classes specified has a stacking value greater than one (specified
with the STACK subparameter or within a dump class definition), DFSMShsm
uses its dump stacking process to stack one or more dump copies on
each dump volume selected.
- If you specify DUMP but not DUMPCLASS, and at least one of the
dump classes associated with a specified storage group has a stacking
value greater than one, DFSMShsm uses its dump stacking process to
stack one or more dump copies of the volumes in that storage group
on dump volumes in the associated dump classes.
- For any dump class with a stacking value of one (specified on
the command or within a dump class definition), DFSMShsm limits that
class's dump volumes to one dump copy per volume.
- If you specify DUMP but not DUMPCLASS, then depending on how storage
groups and their associated dump classes are defined, DFSMShsm may
not dump the eligible volumes in the order in which the storage groups
are specified. In particular, if the dump classes for a given storage
group do not specify stacking, the volumes of
that storage group are dumped (one dump copy per dump volume) after
the volumes of those storage groups using stacking.
- Dump copies of volumes in more than one storage group (specified
on the same BACKVOL command) can be stacked on a given dump volume.
- All stacking to a given dump volume is done while that tape is
mounted. DFSMShsm always selects empty dump volumes to mount as targets
for DUMP.
- When you use BACKVOL to dump one or more storage groups, DFSMShsm
treats all volumes being dumped as having affinity to the host issuing
the command which means that they are all processed on the single
host where the command is submitted.
- If a batch job issues the WAIT BACKVOL STORAGEGROUP command, DFSMShsm
processes the command, but does not ensure that the action completes
before returning control to the caller. As a result, it is possible
for the batch job to complete with return code zero before all of
the volumes are processed.