The systems administrator must decide which VSAM user data sets
are eligible for BWO, and then set up the appropriate operating procedures
for taking the BWO backup copies and for forward recovery.
These procedures include:
- How to forward recover a data set by using the BWO backup copy, the forward
recovery log, and CICS® VR to bring the data set to a point of consistency.
Users must not have access to the file during the recovery process.
- How to forward recover a data set that might have been damaged while allocated
to CICS.
This operation might require backout of partially committed units of work
during CICS emergency
restart, after forward recovery has been done.
The procedures are simpler when using BWO than when not, because:
- Backups can be taken more frequently, so there are fewer forward recovery
logs to manage. This also reduces the amount of processing that is required
to forward recover the data set.
- The point from which forward recovery start is recorded in the ICF catalog. CICS VR
uses this value to automate this part of the forward recovery process. This
recovery point is saved with the backup copy and subsequently replaced in
the ICF catalog when he backup copy is restored.
- During data set restore and forward recovery processing, CICS does not
allow files to be opened for the same data set.