ABCs of z/OS System Programming Volume 3 - IBM Redbooks

4.60 DFSMShsm: Availability management
SMS-managed Non-SMS-managed
Storage Groups
(volumes)
DFSMShsm
Backup
Functions
TAPE
Figure 4-71 DFSMShsm availability management
Primary and
Secondary Volumes
Availability management
DFSMShsm backs up your data, automatically or by command, to ensure availability if
accidental loss of the data sets or physical loss of volumes should occur. DFSMShsm also
allows the storage administrator to copy backup and migration tapes, and to specify that
copies be made in parallel with the original. You can store the copies on site as protection
from media damage, or offsite as protection from site damage. DFSMShsm also provides
disaster backup and recovery for user-defined groups of data sets (aggregates) so that you
can restore critical applications at the same location or at an offsite location.
Note: You must also have DFSMSdss to use the DFSMShsm functions.
User
Catalog
Control
Data
Sets
Availability management ensures that a recent copy of your DASD data set exists. The
purpose of availability management is to ensure that lost or damaged data sets can be
retrieved at the most current possible level. DFSMShsm uses DFSMSdss as a fast data
mover for backups. Availability management automatically and periodically performs functions
that:
1. Copy all the data sets on DASD volumes to tape volumes
2. Copy the changed data sets on DASD volumes (incremental backup) either to other DASD
volumes or to tape volumes
DFSMShsm minimizes the space occupied by the data sets on the backup volume by using
compression and stacking.
Chapter 4. Storage management software 205