Memory Utilization on Windows

[Former Member]

Hi,

   I am having SAP system on Windows server. Physical memory is 64 GB with SAP and DB are running on same host. Recently I observed that processes are not using all assigned extended memory and going in priv mode.

Current Parameters:

ztta/roll_first = 1

ztta/roll_area = 2000000

em/initial_size_MB = 10240

ztta/roll_extension = 2000000000

em/address_space_MB = 520

Processes are only using 520 MB extended memory and going in priv mode. I wanted to know that is it because of em/address_space_MB set to 520?

roll_extension is 2 GB but processes are using around 500 MB and going in priv mode.

Total extended memory utilization is not more than 4 GB so there is enough space available in extended memory.

I have searched many notes but not getting exact answer for parameter - address_space_MB. If I set em/address_space_MB to 2 GB, will it resolve my problem.

Pls suggest.

[bin_sun]

The issue is exactly by setting em/address_space_MB = 520.

Default value of  em/address_space_MB is 4096,

so please just remove the parameter from instance profile,

then em for a wP can be used to ztta/roll_extension.

[Former Member]

Thanks all for suggestion. I'll remove parameter em_address_space from instance profile.

[former_member144433]

Hi,

The memory allocation sequence for a DIA work process is:

1. Roll memory up to ztta/roll_first
2. EM memory up to ztta/roll_extension or until total Extended memory
exhausted(em/max_size_MB in linux)
3. Difference ztta/roll_area minus ztta/roll_first
4. HEAP memory up to abap/heap_area_(non)dia or until total Heap memory
exhausted(abap/heap_area_total)

As there are many work process in PRIV status (using heap memory), it
seems that the problem lies on the extended memory of the instance being
exhausted. Note 941735 should be helpful.

The PRIV mode results either from the lack of extended memory (EM) or
because the memory quota of the work process has been reached
(roll_extension). If this memory is already used (you can check this in
transaction ST02), the work process can only use heap memory for further
processing. Unfortunately, this means that the last user is permanently
using this work process and does not release it, because the heap memory
is work process local memory and therefore not accessible from other
work processes.

Please increase the total size of EM in the instance if there are
enough memory resources in the server. Please refer to note 146289
for additional information regarding the memory parameters involved.

#146289 - Parameter Recommendations for 64-Bit SAP Kernel

#425207 - SAP memory management, current parameter ranges

Thank You.

Regards,

Deepika

[Former Member]

Hi,

You really need to read and apply note 88416 which is the definitive guide for Windows Zero Memory Management.

https://service.sap.com/sap/support/notes/88416

This will help you set the parameters correctly.

Regards,

Graham

[Former Member]

Thanks Graham for your reply. I have already gone through SAP Note 88416 and parameters are set correctly. The problem I am facing is processes are not using complete allocated extended memory and going in priv mode.

What would be the reason for this?

Thanks....

[Former Member]

Yes,

em/address_space_MB is the Size of extended memory pool.  In your case, you have set this at 520MB so beyond this it will go into PRIV mode.

What does your EarlyWatch report for this system say?  Today I have one for my SolMan system on SQL/Windows which recommends that I delete the parameter completely.

Regards,

Graham

[Former Member]

Hi Graham,

In that case what is the use of ztta/roll_extension which is set to 2 GB. There is no suggestion in EWA related to em/address_space_MB.

Thanks