IBM SC34-7012-01 manual Removing BWO attributes, Systems administration, Batch jobs, Procedure

Removing BWO attributes

If you want to remove BWO attributes from your data sets, you must follow the correct procedure to avoid problems when taking subsequent back ups.

Procedure

1.Close the VSAM data set either by shutting down CICS normally or issuing the command CEMT SET FILE CLOSED. Do not perform an immediate shutdown, as CICS does not close the files and the status of BWO does not reset. The BWO status of your data sets will not be correct when you restart CICS.

2.Alter the attributes for the data set to remove the BWO options. You can use the IDCAMS ALTER NULLIFY BWO command.

3.Restart CICS or reopen the data set.

Systems administration

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 should include:

vHow to forward recover a data set by using the BWO backup copy, the forward recovery log, and the forward recovery utility to bring the data set to a point of consistency. Users must not have access to the file during the recovery process.

vHow to forward recover a data set that may have been damaged while allocated to CICS. This operation may 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:

vBackups 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.

vThe point from which forward recovery should start is recorded in the ICF catalog. The forward recovery utility 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 the backup copy is restored. For more information, see “Recovery point (non-RLS mode)” on page 216.

vDuring data set restore and forward recovery processing, CICS does not allow files to be opened for the same data set.

Batch jobs

During the batch window between CICS sessions, it is possible for batch jobs to update a data set. Because batch jobs do not create forward recovery logs, any update that is made while a BWO backup is in progress, or after it has completed, would not be forward recoverable. Therefore, non-BWO backups should be taken, at least:

vAt the start of the batch window so that, if a batch job fails, it can be restarted; and

vAt the end of the batch window, for use with CICS forward recovery processing.

All update activity against the data set must be quiesced while the backups are taken, so that DFSMShsm can have exclusive control of the data set.

208CICS TS for z/OS 4.1: Recovery and Restart Guide