used memory WP

[Naor_Shalom]

HI,

I have a few questions regarding memory management in SAP system.

I read about it a lot butI still confused

My question is:

1. How I know how much memory all the WPs is used? (How much memory all the WPtakesfrom the OS)

2. How I know how much memory all the DIA's is used? (How much memory all the DIAtakesfrom the OS)

Idontwantseperateit to extend memory roll areaetc, I want to know percentage of memory all the WP takes from the OS.

I asked it becauseineed to increase the number of DIA in the APO system, but before the change I want to know how much memory the WP and the DIA used now, I want to avoid frommemory problemin the OS afteriincrease the number of DIA.

My server is always around 80% memory used, but I limit the memory used bySAP systemwith the parameter PHYS_MEMSIZE, and Idontthink the SAP takes all the PHYS_MEMSIZE parameter value.

And it'stakeme to the 3 question:

3.howI know how much memory the SAP system takes fromOS? I limit the memory used by SAP with PHYS_MEMSIZE, but I want to know exactly how much memory the SAP takes and if he used all the valueigive in the PHYS_MEMSIZE.

Maybe Idontneed to increase memory in the server just to increase the number of DIA

Thanks for your help my freinds

Naor

[yakcinar]

Hello Naor,

As you may know ST02 Tx is the place where you need to check about memory usage in SAP instance.

Let me try to explain the topic with some parameters and formulas;

Here is the total memory usage for an SAP System including DB. Maximum usage of the memory can be found using this formula.

Total Memory Used by SAP & DB =

      DB memory  (rule of thumb 1/3 of Host memory)  +

      (Total Alloc KB in ST02 – Total Freesp. KB in ST02) +

      Roll Area Max Use in ST02 second table +

      Page Area Max Use in ST02 second table +

      Extended Mem Max Use in ST02 second table +

      Heap Memory Max Use in ST02 second table

You cannot calculate the max usage of memory using dia or non-dia wps count because all wps use a shared extended memory. There are parameters to limit the usages of this extended memory for each wp like ztta/roll_extension. You can check the usage and allocation of these parameters in ST02 transaction.

SAP keeps local memory of each wps very small in order all wps to use shared memory. For performance and usage reasons.

One more thing that needs care is;

Under normal conditions heap area usage is not accepted. If a wp is using heap memory it means it is in PRIV mode. And using unshared memory area. This is not wanted. This is limited with abap/heap_area_total parameter.

You can check below link for a presentation.

     SAP Memory Management

Regards,

Yuksel AKCINAR

[Naor_Shalom]

Dear Yuksel

You can help with this:

DB memory  (rule of thumb 1/3 of Host memory)  + ST04?

(Total Alloc KB in ST02 – Total Freesp. KB in ST02) + where ifind this in ST02? thefirst table?