DB2 fix : ADM4500W A package cache overflow condition has occurred.

19 January,2016 by Tom Collins

Question: During some troubleshooting , I noticed these messages in the db2diag.log file and instance.nfy files.

“There is no error but this indicates that the package cache has exceeded the configured maximum

size. If this condition persists, you should perform additional monitoring to

determine if you need to change the PCKCACHESZ DB configuration parameter. You

could also set it to AUTOMATIC.”

I checked the database configurations via :

db2 get db cfg | grep ‘PCKCACHESZ’

Package cache size (4KB)                   (PCKCACHESZ) = (MAXAPPLS*8)

How can I get rid of these messages? Do they point to deeper problem?

Answer: First thing to note is it isn’t an error.

The value you’ve presented is refered to as a “soft limit” – which means it can be exceeded if more memory is available.

I think (not  100% sure) this overflow message is written when STMM is not tuning the package cache.

Regarding the displaying of this message – I’ve extracted from the DB2 manual this relevant piece of information:

When this parameter is set to AUTOMATIC, it is enabled for self tuning. When self_tuning_mem is set to ON, the memory tuner will dynamically size the memory area controlled by pckcachesz as the workload requirements change. Because the memory tuner trades memory resources between different memory consumers, there must be at least two memory consumers enabled for self tuning in order for self tuning to be active.

If STMM is enabled and PCKCACHESZ is set to automatic , then the message should not appear.

If you think the some tuning issue exists – set up some regular monitoring using db2pd –mempools  and analyse for any correlations with messages appearing in db2diag.log or even the STMM logs

Read More on troubleshooting

db2pd troubleshooting guide - DBA DB2

DB2 Instance Memory and dbptnmem - DBA DB2

Author: Rambler(http://www.dba-db2.com)


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