SAP on Windows Memory management

[antonio_voce]

Hi all,

I have a question about SAP on windows memory management , and I want report here a real case of a server ( my quality server SAP 4.71 sql2005).

I start SAP and in windows task manager I see 3,5 GB of memory allocated , and now i am tring to understand how this INITIAL allocated space is divided:

1,1 GB to the database ( sql 2005 ) / NTprocess SQLSERVR.EXE

0,512 GB initial size of SAP extended memory ( em/initial_size_MB ) /

no NT process in task manager / this size can increase

dinamically

713 MB is the sum of all SAP buffers ( program, tables, etc. ) that I

can see in ST02 / no NT process in task manager

353 MB for the Windows operating system (when sap and sql are

down )

821 MB is the sum of sap work process ( disp+work.exe ) that are so

divided :

41 MB disp+work.exe

36 MB disp+work.exe

41 MB disp+work.exe

30 MB disp+work.exe

29 MB disp+work.exe

57 MB disp+work.exe

170MB disp+work.exe

.......and so on up to a total of 14 WP ( as

defined in RZ10 )

So , the questions are :

1.How SAP or me decides the initial size of disp+work.exe process ?

2. Wath are the profile parameter that determines the initial size of WP ?

3. If the initial size of WP is determined by fixed profile parameters, why in the task magager the disp+work.exe are so different in dimension ?

Thank' to all in advance!

Edited by: Antonio Voce on May 20, 2008 3:47 PM

[markus_doehr2 · Accepted solution]

Please check

88416 - Zero administration memory management as of 4.0A/ Windows

1002587 - Flat Memory Model on Windows

Markus

[antonio_voce · Accepted solution]

Hi Markus ,

I read carefully the 2 note mentioned, but I again don't understand how sap calculate 821 MB sum of disp+work.exe.

Is is impossible to determine the memory that sap assign to this work process ?

SAP assign all this memory automatically ?

Thank you in advance.

[markus_doehr2 · Accepted solution]

You have a fixed amount of memory for each work process (buffers you configure) + the amount of data the user needs to work with.

So those "821 MB" are buffers + user data. If a user e. g. creates a list with 1000 entries, this will consume a certain amount of memory. If a user creates a list with 10000 entries, he will use more memory. So the actual memory "used" is not fixed, it will vary depending on what user did what with the specific work process.

Markus

[antonio_voce · Accepted solution]

Markus

I am in accord with you , but I don't tell you that this memory assignements , are initially when nobody is logged to SAP and SAP is just start !

So there is not user data in this case.

Assuming that the 821 MB are not the buffers SAP ( the buffer you can see in ST02 ) like Nametab (NTAB), Program, tables etc. thath already occupies 713 MB....

do you know what buffer are ?

Thank you !

[markus_doehr2 · Accepted solution]

> I am in accord with you , but I don't tell you that this memory assignements , are initially when nobody is logged to SAP and SAP is just start !

Yes - because during system start, some of the workprocesses to initilization work (such as checking updates, jobs status' etc.)

> So there is not user data in this case.

Not really true (see above)

> Assuming that the 821 MB are not the buffers SAP ( the buffer you can see in ST02 ) like Nametab (NTAB), Program, tables etc. thath already occupies 713 MB....

> do you know what buffer are ?

If you have abap/buffersize 450 MB then those 450 MB are pre-allocated to put in ABAP programs. On top of that come all the other buffers.

Markus

[antonio_voce · Accepted solution]

ok , I understand the first 2 points of your answer, its true!

Regard the third point you mean tha my abap/buffersize 300 MB in my case, is preallocated two times ? first in the 713MB ( see my first mail ) and second time also in the disp+work.exe processes that occupies totally 821 MB ? And so on for the other buffer ?

NB : my memory allocation is as I write in my first mail :

1,1 GB to the database ( sql 2005 ) / NTprocess SQLSERVR.EXE

0,512 GB initial size of SAP extended memory ( em/initial_size_MB ) /

713 MB is the sum of all SAP buffers ( program, tables, etc. ) that I

can see in ST02 / no NT process in task manager ( abap/buffersize )

353 MB for the Windows operating system (when sap and sql are

down )

821 MB is the sum of sap work process ( disp+work.exe ) that ....

TOTALLY 3,5GB ( windows task manager )

Thank you in advance Markus .

[markus_doehr2 · Accepted solution]

> ok , I understand the first 2 points of your answer, its true!

> Regard the third point you mean tha my abap/buffersize 300 MB in my case, is preallocated two times ? first in the 713MB ( see my first mail ) and second time also in the disp+work.exe processes that occupies totally 821 MB ? And so on for the other buffer ?

Not two times! The buffer itself IS the 450 MB (or the 300 MB). It's not allocated because you define it but it's allocated on workprocess start. That memory is shared across the processes so each process "attaches" to it and it may appear that the memory used of all workprocesses is more than the machine can have. This is not the case

> NB : my memory allocation is as I write in my first mail :

>

> 1,1 GB to the database ( sql 2005 ) / NTprocess SQLSERVR.EXE

> 0,512 GB initial size of SAP extended memory ( em/initial_size_MB ) /

> 713 MB is the sum of all SAP buffers ( program, tables, etc. ) that I

> can see in ST02 / no NT process in task manager ( abap/buffersize )

> 353 MB for the Windows operating system (when sap and sql are

> down )

>

> 821 MB is the sum of sap work process ( disp+work.exe ) that ....

>

> TOTALLY 3,5GB ( windows task manager )

821 MB is em/initial_size_MB + the disp+work.exe + runtime libraries + the "attachment" to the shared memory + workprocess local buffers for usercontexts.

Markus

[antonio_voce · Accepted solution]

Markus,

now i understand , thank you very much for the explanation.

See you soon.

Antonio.