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The forward recovery utility should ALLOCATE, with DISP=OLD, the data set that
is to be recovered. This prevents other jobs accessing a back level data set and
ensures that data managers such as CICS are not still using the data set.
Before the data set is opened, the forward recovery utility should set the BWO
attribute flags to the ‘Forward recovery started but not ended’ state. This prevents
DFSMShsm taking BWO backups while forward recovery is in progress. To prevent
CICS opening a back level data set, the utility should perform this state change for
all data sets in a system that supports BWO, even if some do not use BWO.
The forward recovery utility should use the BWO time stamp for the data set in
the ICF catalog, set by DFSMSdss when the data set is restored, to determine the
starting point in the forward recovery log to start the forward recovery.
If forward recovery completes successfully, the utility should set the BWO
attributes to the ‘BWO disabled’ state before the data set is closed.
If forward recovery does not complete successfully, the utility should leave the
BWO attributes in the ‘Forward recovery started but not ended’ state to ensure that
CICS does not open a back-level data set.
If forward recovery does not complete successfully:
1. Determine and correct the reason for the failure
2. Delete the partially-recovered data set
3. Restore the backup copy
4. Reattempt forward recovery
Note: The EXEC CICS SET DSNAME RECOVERED system programmer command
(or the CEMT equivalent) resets the BWO attributes in the ICF catalog to indicate
‘BWO disabled’. If you use this command for a data set that has been restored but
not forward recovered, and then you subsequently open this data set, CICS will be
unaware that forward recovery has been overridden and CICS may access back
level data. However, in exceptional circumstances, it may be necessary to allow
CICS to access back level data. This command has been provided to allow this to
happen.
Alternatively, if you use a VSAM forward recovery utility that does not update the
BWO attributes during forward recovery, you may use these commands to reset
the backup-restored-by-DFSMShsm state before subsequent CICS file control
access.
Recovering VSAM spheres with AIXs
Before you can forward recover a data set that was restored from a copy made
using BWO, ensure that no AIXs are in the upgrade set. CICSVR checks the
upgrade set of data sets restored from BWO copies and issues a message if AIXs
are found.
About this task
To forward recover such a data set, after the restore, use the AMS ALTER or
DELETE command to remove or delete the AIXs from the upgrade set. After
forward recovery has completed successfully, you can re-create the upgrade set by
rebuilding the AIXs using the access method services BLDINDX command.
Chapter 18. Backup-while-open (BWO) 217