RAM memory is not freeing after close any runtime program

[former_member235282]

Dear experts,

I have this situation:

During any  program  runtime in a CRM system, the work process (WP) uses  the full memory assigned, after kill the processes or finishing them abruptly,  the  RAM memory   is not freeing. I can see this when I check the memory status in the operative system (AIX). Apparently, the operative system is not identifying  when the WP  release the memory to use it again.

The reason to  kill the processes is  because in an operation where I have 10 thousands users accesing to the system (rush hours) I have been in the situation of releasing some  load of the system manually (finishing process by myself or asking to the users that are spending more runtime  to close what they are doing) when system memory starts paging.  This process is useless because the OS  is not able to  use that memory again with  other users or processes  because the memory still appears as used. The only way is  refreshing  the system with a server restart.

Other problem that we have is that the load balancer is not  balancing properly, this lends itself for increasing the problem.

Details,

• The system landscape: 5 application servers, one enqueue, one webdispatcher, 2 database node in RAC.

• SAP Netweaver 7.01

• Operative system: AIX

• Database:Oracle 10G

I have some doubts around this situation,

1. Where is the root cause of this problem,  In the Work Process  or in the OS? In any case, does anybody know the workaround?

2. Is there any work around to refresh the memory without restart  the server?

3. Any other suggestion? Memory parameters?

If someone needs more information  (logs, printscreen) for further analysis please let know.

I appreciate any comments,

Regards,

DanielO

[Former Member]

Hi Daniel,

General but important question: Is you kernel up-to-date?

Do you get dumps related to the issue?

Check also:

https://help.sap.com/saphelp_erp60_sp/helpdata/en/f6/3e63cd45bc4d6d80c4ee45d12f9884/content.htm

Regards,

Serhat

[Former Member]

Hi Daniel,

This does look like an issue.  First check whether you have a current kernel.  If not, install it as kernel updates tend to resolve memory issues.  Also get your AIX people involved.  Many OS's use 'free' memory to cache information.  Thus memory can appear full though some of it is being used by the OS. This cached memory will be released to the applications as and when they need it.

Is the paging causing you a performance issue?  It's usually swapping that is your main area of concern.  Paging is standard whereas swaps occur because there is no memory free to perform the task at hand.

Have you set the WP's to automatically restart periodically?  That is a standard function which might help you.  Of course, any WP that goes into PRIV mode will restart automatically on conclusion of the task anyhow.

Are you seeing additional wait times?  If so, you might need more WP's.

Let us know how you get on.

Regards,

Graham

[manumohandas82]

Hi Daniel ,

Check the following Note

1972803 - SAP on AIX: Recommendations

4b) Unexplainable usage of physical memory

A main important aspect of AIX memory-management is that parts of the physical memory which are not used by any processes or the Operating System (both together give the "active virtual memory") can typically be utilized by the file cache. The latter will typically give immediately back most of it's occupation in case the active processes demand for more memory. So it can be misleading just to look at the memory's free list when checking for spare resources but also the file cache is to be taken into account. That all is discussed in detail in Note 1971698.

Thanks ,

Manu