SAP Netweaver Java AS JVM settings and Paging File size

[Former Member]

Hello experts,

In our production Enterprise Portal system, we have 8 App servers(each with 3 server nodes) and 3 DB servers on a 32 bit Windows Server 2003 Enterprise Edition with CPU Count at 4 for each server. We have 8 GB of RAM available for usage. I know that being a 32 bit system, there is a limit to the heap size that can be used for the app servers

The paging file size for  6 out of 8 app servers is 8176MB and other  two has 12286MB and 12000MB

Very soon the RAM will be increased from 8 GB to 16 GB.

I have gone through the note 723909, but it  recommends 1GB heap size for 32 bit system.

1. Can i increase it to 2 GB ? If not, then will it be best to add server nodes ?

2.  If i increase the paging file size will it help?

Please advise.

Thanks a lot for your help!

[Former Member · Accepted solution]

As per note I would not recommend to add more than 1 GB heap size. The best option is to add more server nodes.

Check how much paging is used and depending on the utilization you can add more paging if required.

[Former Member]

Dear Anupama

First of all it is not recommended by SAP to use 32bit machine for PROD systems. Please refer sap note 996600 32 Bit platforms not recommended for productive NW2004s apps.

For 32bit systems, maxheapsize you can configure is 1.5GB. Best option is to increase server nodes than increasing heap size.

I hope this helps

Tapan

[Former Member]

Hi Tapan,

Migration to 64 bit OS will happen only by mid next year, till then i have to keep the 32 bit system healthy and fine!!

Thanks, yes that was helpful

Regards,

Anupama

[former_member191911]

Pay extra attention to this statement in the note:

For each JavaVM on the server, all Java memory must fit completely into physical memory (no paging)!

Paging heavily influences the stability of the java stack, so I would try at any time to avoid configuring more memory than physical available.

Kr. Mark

[Former Member]

Hi  Sunil and Mark,

Many Thanks for responding.

Agreed, that increase in heap memory will lead to increased paging, and i am new to Portal Administration, so was wondering, if the paging size is increased, will it allow to add more heap memory to the server nodes.

A migration to 64 bit is going to happen only by mid next year and till then we are struggling with the performance. Currently,

* Max CPU load is somewhere near 20% (which i think should be ok)

* Paging Rate is a little high - Page In (% RAM per hour ) is 1250% (Max value)

                                            Page Out rate is high in Central Instance

So then, i would like to ask:-

1. Adding server nodes will help in improving the performance in my scenario?

2. To handle high paging rate, is paging file size sufficient? What could be ideal page file size once the RAM is increased from 8 GB to 16 GB?

Thanks again for your responses. It did help me a lot!!

Regards,

Anupama

[former_member191911]

Hi Sunil,

I would only increase the number of server nodes if sufficient memory is available to do so.

To be sure if more resources are required, you should investigate the performance of the portal with Wily Introscope. This tool provides you a good insight onto what is going on inside the java stack.

It could very well be that the performance degradation is being cause by bad sql statements, missing statistics on tables/indexes, java threading, etc.

If the current page file is not being used extensively, I would not increase it after you uplift the physical RAM from 8 to 16GB.

Kind regards,

Mark