Use the Recovery Estimator
The Recovery Estimator determines whether Db2 objects are recoverable and it provides an estimate for the recovery time.
The Recover Estimator analyzes the recoverability of a Db2 object or group of objects and estimates the time it would take to recover them. Database administrators can use this batch utility to verify that recovery service level agreements (SLAs) are met.
The Recovery Estimator can analyze databases, tablespaces, tables, indexspaces, and indexes. When the utility is executed, it generates a report that provides the following details for each object:
- Whether the object is recoverable
- The image copies that were used for the estimate
- The size of the logs that were used for the estimate
- The estimated recovery time for the object
- Whether the image copies and logs are cataloged (if VERIFY-DATASETS is used)
The Db2 objects and copy data sets are untouched during the estimation and verification process. Instead, the Recovery Estimator retrieves the object information from the SYSIBM.SYSCOPY and SYSIBM.SYSLGRNX tables.
Sample JCL for the Recovery Estimator is provided in
Before you use the Recovery Estimator, consider the following points:
- The Recovery Estimator reports COPY NO indexes as NOT RECOVERABLE. Depending on the recovery utility that is used, these indexes may be recoverable. For example, if you useCA Fast Recover™ for DB2 for z/OSwith AUTO-IX-REBUILD YES, these indexes would be rebuilt automatically during a recovery.
- The estimated recovery time does not factor in the utility that would be used to perform the recovery.
- The recovery time for each object is estimated independently. The estimated time does not factor in resource constraints such as multiple objects being run in parallel.
- The Recovery Estimator assumes that the information in SYSCOPY and SYSLGRNX is accurate. The Recovery Estimator does not verify that the image copies and logs exist and are usable. To verify that the recovery is possible, use the recovery simulation feature in CA Fast Recover. The simulation performs the entire recovery process to shadow data sets, which confirms resource usability.
Follow these steps:
- Copy the FRECOEST member inhlq.CDBAJCL and open the copy for editing.
- Edit the JCL as follows:
- Update the JOB statement as needed for your site.
- Update the RECOVER-TOOL ESTIMATE-RECOVERY control statement to specify the objects to include in the estimation and the recovery point.
- Add other syntax options as needed.
- Submit the job.The Recovery Estimator utility analyzes the specified objects and writes a Recovery Estimation report to the job log.
- Review the Recovery Estimation report and address any warnings that are shown.
- (Optional) Run aCA Fast Recover™ for DB2 for z/OSjob to verify that the recovery is possible. (A recovery simulation, unlike the Recovery Estimator, verifies that the resources exist and are usable.) Sample JCL for a recovery simulation is provided inhlq.CDBAJCL(FRECOSIM). The job must have the following syntax:
CA Fast Recover performs the recovery simulation and writes the results to the job log. For more information about recovery simulations, see Simulate an Object Recovery.
- A RECOVER statement that specifies the same objects that were analyzed by Recovery Estimator
- The PREVIEW SIMULATE keyword to simulate the recovery
- (Optional) The KEEP-SIMULATION-SHADOWS keyword to keep the shadow VSAM data sets when the simulation is done