Improving recovery time

To recover an application as quickly as possible after a failure, perform as much object set processing as possible before recovery becomes necessary.

In particular, perform the following tasks:

  • Whenever possible, create object sets before a potential recovery and routinely update and revalidate their recoverability. In the case of recovery to a prior point in time, you should ensure that indexes and objects that are related by referential integrity are included in the object set.

Related topic

Performance-considerations

  • Run the RUNSTATS utility as often as needed to keep Db2 catalog statistics current. Out-of-date catalog statistics can adversely affect both the accuracy of the JCL and the time that is taken to generate it. Alternatively, keep BMCSTATS information up-to-date using DASD MANAGER PLUS or BMC AMI Copy, and set the appropriate sizing option to instruct BMC AMI Recovery Manager to use those statistics instead of catalog statistics.
  • Run the RUNSTATS utility on the repository to improve performance if the online performance seems slow.
  • In general, when the recovery of an object set becomes necessary, always revalidate the recoverability of the object set and then generate and submit the JCL. JCL that is generated at an earlier time may be inaccurate.
  • Use multiple job optimization wherever possible to provide the best overall recovery time. See Multiple-job-optimization for more information.
  • When recovering an entire table space, do not split it by partition unless you make copies by partition and one of the following scenarios applies:
    • You are using DSNUTILB as the recover utility.
    • You are using multiple job optimization.
    • You are using the BMC AMI Recovery Manager UNLOADKEYS/BUILDINDEX strategy.
  • Limit SYSIBM.SYSCOPY searches to avoid unneeded input/output (I/O) operations and memory use. You can set the value of the LIMIT_SYSCOPY_SEARCH option to limit the period that BMC AMI Recovery Manager searches the table for a requested copy or quiesces point. If you do not set this value, BMC AMI Recovery Manager does not limit the search. For more information, see Recovery-utility-options.
  • Always consider generating recovery JCL in batch mode instead of performing this task online. Doing so frees up your terminal during processing.
  • Include indexes and objects that are related by referential integrity only for point-in-time recoveries or when you generate JCL for disaster recovery.
  • Choosing BMC utilities can provide a significant improvement compared with IBM utilities. Also, choosing BMC AMI Recover as your recover utility lets you perform recovery simulation.
  • Avoid backing up objects with no changes since the previous backup. Avoid recovering objects that have not changed since the recovery point in time. Use the XUNCHANGED option in ARMBGEN or the Unchanged option on the online panels.

 

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