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

[Naor_Shalom]

HI.

First Iwant to thanks for your help

So if I understandcorrect thereis no way to know what is exactly the used memory of the WP\DIA?

And what about the all SAP memory?

I ask you another question.

Let's say you need to increase DIA in your sap system. whatdo you check before you do it, from the memory side, to be sure you will not have memory issue.

Thanks Naor

[yakcinar]

Hello Naor,

Answers are below

So if I understandcorrect thereis no way to know what is exactly the used memory of the WP\DIA?

- Yes, at startup wps allocates some memory but it is neglectable when wp is in wait status. Whenever a user runs an activity on that wp it allocates memory from extended memory with a limit roll_extension. When it finishes it uses heap memory to a limit also.

You can chek below links

Memory Management: Basic Concepts - Architecture of the VM Container - SAP Library

Virtual Address Space of a Work Process - SAP Memory Management (BC-CST-MM) - SAP Library

SAP Memory Management (BC-CST-MM) - SAP Library

Allocating Memory for User Contexts (UNIX) - SAP Memory Management (BC-CST-MM) - SAP Library

And what about the all SAP memory?

Use the formula to find total SAP memory usage. I add screenshot of ST02.

I ask you another question.

Let's say you need to increase DIA in your sap system. whatdo you check before you do it, from the memory side, to be sure you will not have memory issue.

In this situation if you donot change memory parameters total SAP memory usage will not change. Or change is neglactable. Very small. All wps will use extended memory. If it is exhausted you will get memory dumps. And some programs will use HEAP area till limit also.

Increase #of wps and monitor your system from ST02 and ST22. Check PHSY_MEMSIZE parameter if you increased host memory. On windows this parameter is automatically set by SAP so you can check zero memory management note for windows.

Regards,

Yuksel AKCINAR

[Naor_Shalom]

Dear Yuksel

So if I want to know all the sap memory

I calculate this formula

max total allocated + max total freespace + max uses = all sap memory ?

Thanks

naor

[yakcinar]

Hello Naor,

Use this formula. There are minuses as well.

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

Can you send your ST02 as screenshot and as text also. And current memory parameters. I will try to calculate it for you.

Regards,

Yuksel AKCINAR