sap extended memory showing inmemory only

[Former Member]

Hi all,

We are on ECC 6.o on Redhat linux  with DB2 9.7

I have observed all our extended memory is showing as in memory not in disk, i am not able to find the reason why it's was  occupying the primary memory all.

Please suggest how to distubute the extended meory to disk  from in memory..

Thanks,

Subhash.G

[Former Member]

In my opinion SAP does not track which part of extended memory was allocated/moved to swap (paging) space. OnDisk column used to show Roll Area/Page Area actual usage only. This is only my opinion after some research

Regards

Roman

[Former Member]

Hi,

We have currently 10 GB of allocated ram now, if any  BDC load jobs ran the heap is completly getting full and going to extended and making system very slow to respond ...

We are trying to increase the swap space and heap memory for non-dia and decrease the usage of extended memory by batch jobs.....

Is there any better option we can try ...? please suggest

Thanks,

Subhash.G

[Former Member]

Answer to your question can not be described in few words. This issue is not so trivial. At first try to optimize your BDC load jobs to consume less memory if it is possible. Check memory utilization at system level and if memory is overcommitted increase ram. Increasing swap space (at OS level) will not solve your performance problem.

Regards

Roman

[former_member189725]

The heap will get full as the non-dia workprocesses will consume heap memory and then go on to use extended memory. It seems the physical memory is almost  consumed and swap space is being used . This is leading to slow response as data has to be swapped in to the main memory often. Suggest you to  increase the main memory or reduce the data volume in BDC load jobs or run them at low activity period.

Regards

Ratnajit

[former_member189725]

The extended memory which is defined by the parameter em/initial_size_mb is a memory pool which is allocated from the virtual memory (Physical memory+swap space) . When the instance starts up , this entire pool of extended memory is allocated which in your system is 8 GB. If there is enough physical memory available in the system, then the allocation would be completely on the physical memory and no swap space(on disk) would be used. Using the swap space would reduce the performance of the system as the data needs to moved in from the swap region to the physical memory during an operation. I am not sure as to why you purposefully want to utilize the swap space.

The swap space basically ensures that your system has enough virtual memory in case your physical memory is small and applications do not run into issues like segmentation fault.

If you extend the  em/initial_size_mb to a very high value , then you can see the extended memory using the swap space , else it will be on the physical memory/RAM.

How much of physical memory do you have in your system?

Regards

Ratnajit