Advs & disadvs of Self Tuning Memory Management feature of DB2 v9.5

You can use the STMM feature as a guide for your configuration parameters
but donot keep it ON always. I remember a tuning exercise which I had done
for a client with similar configuration. The STMM had allocated such high
number for pages that the main bufferpool failed to start and system was
using hidden bufferpools hus degading the performance. Hence, just watch
it for a few weeks, note down the parameter sizes and put it off. Then
brainstorm a bit over these values and finally configure your db.
All the best.

--
Message posted using http://www.talkaboutdatabases.com/g...abases.ibm-db2/
More information at http://www.talkaboutdatabases.com/faq.html

Note that your under Windows at DB2 V9.5
At that level with that OS the INSTANCE_MEMORY parm. of your dbm cfg
is critical.
The instance manages all the memory required for DB2.
This includes insrtance memory, database global shared memory, and
memory for all the connected agents and sub agents.
In your case, I'd start all applications except DB2 instance. Look at
the memory left over and that's what you need to give your DB2 (maybe
a bit less) instance.
Then db2start the instance, make sure STMM is on and activate the db.
You then have to operate, without deactivating, for a period of time
(hours or days) depending on how representative the workload you will
run.
You will have to snapshot (db2pd, snapshot routines) to find how your
key memory pools evolve.
When you feel/see that they have stabilized and do not change much
then turn off STMM. Note that the numbers you get to configure your
memory pools are valid for that workload. You may have to change them
or re-enable STMM for maintenance workloads or different types of your
test.
Hope this helps, Pierre.



On Oct 6, 7:38*am, satish mullapudi <satishmullapud...@gmail.com>
wrote: