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formula for SAP system work processes

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Frequent Advisor

formula for SAP system work processes

Hi experts

I have hp-ux 11i server with SAP 3.0f /SAP 3.1I_com kernel and would like to get the formula that will count the number of work processes need to be on the system.
Any body have the formula related to this syste.

I would appreciate any help as it was very difficult to get those information from SAP Service marketplace.

Sanjay Kumar Suri
Honored Contributor

Re: formula for SAP system work processes

There is not formula. However following may help.

R/3 Application Services: Each application server has dispatcher as well as work processes (DVEBS). The R/3 system provides two additional services for internal and external communication.

The message server (MS or M) communicates between the distributed dispatchers within R/3 system.

The gateway server (GW or G) for R/2 and external application systems.

Dialog (D): Every dispatcher requires at least 2 dialog WP.

Spool (S): At least 1 for each R/3 system (more than 1 allowed for each dispatcher).

Update (V): At least 1 for each R/3 system (more than 1 allowed for each dispatcher).

Background processing (B): At least 2 for each R/3 system (more than 1 allowed for each dispatcher).

Enqueue (E): Only one is needed for each R/3 system.

A rigid mind is very sure, but often wrong. A flexible mind is generally unsure, but often right.
Volker Borowski
Honored Contributor

Re: formula for SAP system work processes


basic calculation for a central instance with database on one single host, no application server is very RAM dependant.

If you have no idea about the application load, start with minimal approach. For release 3.x (!!) (assuming Oracle 8.0.x as the database below) this would be roughly:

200 MB DB-Buffers
150 MB Shared pool
~100 MB Spare for Oracle PGA and Oracle-stuff else.

150 MB (!! bare minimum !!) ABAP-programbuffer
~100 MB rest global buffers for the instance
~200-???? MB dynamic Memory for SAP Instance

Now as far as I remember, ~15MB was the amount of memory a single workprocess needed staticly with 3.x. As alread pointed out, the absolute minimum is to have 2 Dialog processes and one of the other types
You do not need to configure additional Gateways if you have no SNA connection, the TCP/IP gateway ia always part of the instances as well as the message server for a central Instance.

OK, now you are ready to calculate what is left. In this config, you have 900 MB for global buffers of any kind plus 6 workprocesses (~ 90 MB) plus some spare for gateway and message server.

This means, you need ~ 1GB. It is possible to run a system with less memory (I have seen 3.X systems on 384MB boxes, but this was just for testing purposes of a handfull of users, and there was not so much fun with that). If you have more RAM available, there are various ways to spend it.

To scale on, you need to decide what your application load is like. If you have many users working in the same SAP modules, you will like to increase the number of dialog and update processes (1 UPD for 3-7 DIA, depending on module and dialog activity).
If you have just few users (< 15-20), but use 3+ modules from SAP, you would like to increase the programbuffer first.

This part is an ongoing process, which develops with the monitoring of the system.

Ensure that the background job RSCOLL00 is running hourly (Jobname usually COLLECTOR_FOR_PERFOMANCEMONITOR or SAP_COLLECTOR....). It gathers performance data to give you somthing to work with.

Check transaction ST04 for quality of DB-buffers (90%+ is ok as a starter) and shared pool (95%+) (if oracle).

Check transaction ST02 for quality of SAP Buffers.

Check transaction ST06 for CPU load and memory consumption. You should ensure that some memory is still free directly after the start of the instance. So the system should not do paging for global memory areas (this would be a real knock out). The bigger the reserve is, the less paging you will have for dynamic memory requirements.

Check transaction ST03 for load distribution of the workprocesses. A wait time higher than 10ms for dialog-task-type suggests to increase the nuber of dialog processes (this rule does not apply for batch:-)

All of the STxx data should be taken more serious the loger the uptime of the sap-instance is. Bufferqualities of 60% are not critical, if the instance has just started. 60% is inacceptable if the system is running for a few days. Some system activities destroy buffer-quality by design, I.e. client-copies. So do not anlyze DB-BUFFER needs after a client copy.... You will never have enugh RAM for that!

Again this is a basic start, and you will need to increase these values with either the number of users / number of used modules / sap-release.

How much RAM do you have ?

Hope this gives you something to work on.
Volker Borowski
Honored Contributor

Re: formula for SAP system work processes


I just saw from your previous questions that you already dealt with application server(s).

Do NOT configure any ENQ on the APP-Servers !

... and keep in mind that an additional workprocess on the application server requires an Oracle shadow process on the database server.