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Catalog maintenance
Problem
What are the rules for maintaining DB2® catalogs? How frequently should I run utilities such as REORG, RUNSTATS, and MODIFY?
Solution
Image copy the catalog as frequently as the most aggressive service level that you have for your application data. For example, in some cases, taking
8 copies a day is a reasonable number. You take one full image copy and make incremental copies in between. Use MERGECOPY to combine the copies.
You need to reorganize the catalog. If you do not reorganize the catalog, it can hurt performance. Run RUNSTATS frequently to determine when to run REORG on the catalog.
Run MODIFY RECOVERY in conjunction with the reorganization of SYSLGRNX and SYSCOPY. Keeping SYSLGRNX organized is very important if you are running online REORG; DB2 depends on the information in SYSLGRNX to determine which log ranges on which members need to be scanned to find the log records for the objects that are being reorganized. If you do not reorganize SYSLGRNX, it hurts performance.
When you migrate to Version 8, you need to reorganize the catalog to enable new-function mode. In Version 8 compatibility mode, you have the ability to reorganize the catalog and directory while DB2® is running (You must use the SHRLEVEL REFERENCE option). During this reorganization, you learn two
things:
How long it takes to reorganize each of your table spaces. The sum of these times is how long it takes DSNTIJNE to run. DSNTIJNE enables new function.
Most of the time is spent reorganizing.
How much space you need for the reorganized catalog table spaces.
Typically, you need no more than 10% more space for the Version 8 catalog.
However, some people saw their catalogs shrink by 50%, because they had never reorganized it.
P.S. Please pass my address to anyone interested in DB2 HOTLINE - thank you.
With kind regards
Michael Dewert, Software Group
DB2 Information Management Software
