IBM SC34-7012-01 Forward recovery procedures, Forward recovery of data sets accessed in RLS mode

Chapter 17. Forward recovery procedures

If a data set that is being used by CICS fails, perhaps because of physical damage to a disk, you can recover the data by performing forward recovery of the data set.

About this task

Your forward recovery procedures can be based either on your own, or an ISV-supplied utility program for processing the relevant CICS forward recovery log streams, or you can use CICS VSAM Recovery. See CICS VSAM Recovery for z/OS for details of forward recovery using CICS VR.

This section covers the following topics:

v“Forward recovery of data sets accessed in RLS mode”

v“Forward recovery of data sets accessed in non-RLS mode” on page 198

v“Procedure for failed RLS mode forward recovery operation” on page 198

v“Procedure for failed non-RLS mode forward recovery operation” on page 201

Forward recovery of data sets accessed in RLS mode

A recoverable data set that is updated in RLS mode can have retained locks held for individual records.

In the event of a data set failure, it is important to ensure that you preserve any retained locks as part of the data set recovery process. This is to enable the locks associated with the original data set to be attached to the new data set. If the data set failure is caused by anything other than a volume failure, retained locks can be “unbound” using the SHCDS FRUNBIND subcommand. The data set can then be recovered and the locks rebound to the recovered data using the SHCDS FRBIND subcommand.

Note: If you use CICSVR to recover a data set, the unbinding and subsequent binding of locks is handled by CICSVR. CICSVR also uses the SHCDS FRSETRR and FRRESETRR commands to prevent general access to the data set during the recovery process.

If a data set failure is caused by the loss of a volume, it is not possible to preserve retained locks using FRUNBIND and FRBIND because SMSVSAM no longer has access to the failed volume. When recovering from the loss of a volume, you can ensure data integrity only by deleting the entire IGWLOCK00 lock structure, which forces CICS to perform lost locks recovery. CICS uses information from its system log to perform lost locks recovery. (For more information about lost locks processing, see “Lost locks recovery” on page 89.) Recovering data from the loss of a volume requires a different procedure from the simple loss of a data set.

The procedures to recover data sets that could have retained locks are described in the following topics:

vFor recovery of failed data sets where the volume remains operational, see “Recovery of data set with volume still available” on page 188

vFor recovery of failed data sets where the volume itself has failed, see “Recovery of data set with loss of volume” on page 189.

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