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

[satish mullapudi]

Hi All,

We are using DB2 v8.2 and are planning to migrate to DB2 v9.5. The
settings of our servers are as follows:

OS: WIN (4 servers) , AIX(1 server)
RAM: 3GB
HDD: 40GB
Other huge s/ws: WAS 6.1, IHS 6.1, other small 3rd party tools ( these
doesn't take much of the RAM.
DB size: 160MB (min size) to 5GB(max size)
Transactions Type : Neither completely OLTP nor completely OLAP. It is
a mixture of these two & they are also not too huge.

I have seen the STMM (Self Tuning Memory Management) feature in DB2
v9.5. I have given my proj. config above. Is it suggestible to go for
STMM feature / customized values for the db cfg params. Pls suggest
me.

Regards,
Satish

[Praveen_db2]

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.

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[Pierre StJ]

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 <[e-mail]>
wrote:

Hi All,

We are using DB2 v8.2 and are planning to migrate to DB2 v9.5. The
settings of our servers are as follows:

OS: WIN (4 servers) , AIX(1 server)
RAM: 3GB
HDD: 40GB
Other huge s/ws: WAS 6.1, IHS 6.1, other small 3rd party tools ( these
doesn't take much of the RAM.
DB size: 160MB (min size) to 5GB(max size)
Transactions Type : Neither completely OLTP nor completely OLAP. It is
a mixture of these two & they are also not too huge.

I have seen the STMM (Self Tuning Memory Management) feature in DB2
v9.5. I have given my proj. config above. Is it suggestible to go for
STMM feature / customized values for the db cfg params. *Pls suggest
me.

Regards,
Satish