IBM SC34-7012-01 Forward recovery logging, Data set restore, Data sets, Non-SMS managed storage

DFSMSdfp must now disallow the pending change to ‘BWO enabled’ (and DFSMSdss must fail the backup) because, if the split did not finish before the end of the backup, the invalid backup would not be discarded.

vFrom ‘BWO disabled and VSAM split occurred’ to ‘BWO enabled’. This state change could be attempted if:

1.At the start of data set backup processing, a request is issued to change the ‘BWO enabled and VSAM split occurred’ state to the ‘BWO enabled’ state.

2.But then, before the ‘BWO enabled’ state is set, CICS closes the last file opened for update, and the data set becomes ineligible for BWO. CICS sets the ‘BWO disabled and VSAM split occurred’ state to ensure that the BWO backup is discarded and that no more BWO backups are taken.

DFSMSdfp must now disallow the pending change to ‘BWO enabled’ (and DFSMSdss must fail the backup) to prevent the possibility of a BWO backup being taken during a subsequent batch window.

Data set restore

When a BWO backup copy of a data set is restored, using DFSMShsm RECOVER or DFSMSdss RESTORE, the data set must be serialized to prevent any updates during the restore operation.

When the restore is complete, the BWO attributes in the ICF catalog are changed to a ‘Backup restored by DFSMShsm’ state. CICS cannot open the data set until forward recovery has been completed successfully.

DFSMSdss also resets the recovery point in the ICF catalog to the value it contained when the backup was made. This ensures that forward recovery starts at the correct point. This value should not be used for forward recovery of a non-BWO backup.

Non-SMS managed storage:

If a BWO backup is restored in storage that is not SMS-managed, the BWO attributes in the ICF catalog are lost. Thus forward recovery is not possible.

Forward recovery logging

The forward recovery utility uses the forward recovery logs to recover a base cluster.

To do this, it must know:

vThe data set to associate with each record on the logs

vThe point from which to start recovery

Data sets

Each data set after-image record on the log is associated with a file name.

However, there might be many files associated with the same data set; therefore, when a file is opened, the association between the file and the data set is recorded on the forward recovery log by a tie-up record. This information is also written to the log of logs. For non-BWO backups, the forward recovery utility uses this tie-up record to apply the log records to the correct data sets.

When a BWO is taken for a data set opened in RLS mode, DFSMSdss notifies each CICS region having an open ACB for the data set. On receipt of this notification,

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