Note 39412 - How Many Work Processes Should Be Configured

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SAP Note 39412 - How many work processes should beconfigured?

Note Language: English Version: 24 Validity: Valid Since 17.08.2010

Summary

SymptomThis note answers the following questions:

o How many work processes must and may be configured?

o How do I see which work processes exist and what they do?

o How do I set the number of work processes?

Other termsRZ04, RZ10, SM63, SM50, SM51, SM66

Reason and Prerequisites*

SolutionDefinition: In this note, "server" is a synonym for "instance".

Technical conditions:

o DIA (dialog):

- Number of processes: There must be at least as many processesas the total of configured non-dialog work processes on thisinstance (also see Note 934109).

- If a J2EE instance (dual-stack instance) exists, the minimumnumber of DIA processes must be 5.

o UPD (update):

- Number of update servers: The update must occur on at least oneserver.

- Release 2.1 and 2.2 :Only configurations with exactly one update server in thesystem are officially supported. The name of this server isdefined by the system parameter rdisp/vbname. At least one UPDprocess must run on this server.

In Releases 2.1 and 2.2, several update servers should be usedonly if absolutely necessary (performance). The parameterrdisp/vbname defines for each server where the update requestsmust be sent. At least one update process must run on each ofthese update servers. Also refer to Note 7209.

- The following applies to Release 3.0:Several update servers are allowed. There must be at least oneupdate process somewhere in the system. The assignment is notcarried out via rdisp/vbname, but is carried out dynamically.

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- If several code pages are used at the same time in one system,there are further restrictions (see the notes under the keyword "MNLS").

o UP2 (update V2 - as of Release 3.0):

- If there are UP2 processes in the system, a V2 update (anupdate with low priority) is possible only in these processes;the UPD processes are then reserved for V1 (an update with highpriority).

- If there are no UP2 processes, the UPD processes take over bothV1 and V2.

- As a result, UP2 processes do not have to exist. However, theV1 update may be delayed if there are no UP2 processes. If youdecide to configure UP2 on an instance, we recommend that youdefine at least TWO UP2 on such an instance.

o BTC (background):

- Number of processes: at least 1 in each system, at least 2during the upgrade

- Reservation of processes for job class A:If n background processes are running, a maximum of n-1processes may be reserved for class A jobs. Otherwise, jobswith class B and C would be blocked (see Note 36280).

o ENQ (enqueue):

- Number of servers: there is exactly one enqueue server in thesystem (system parameter rdisp/enqname)

- Number of processes: One ENQ process must run on the enqueueserver. It may make sense only in certain special cases(extremely large systems) to have more than one ENQ processrunning (on the same instance).

o SPO (spool):

- Number of processes per system: as many as required, at least 1

- Number of processes per server: The following applies to Releases 2.x/3.x: a maximum of 1 The following applies to releases as of Release 4.0A: as manyas required

- See Note 108799 to decide how many spool work processes shouldbe configured.

- Restrictions:Spool processes cannot be switched on and off when switchingbetween operation modes.The following applies to releases up to and including Release2.1J and 2.2D: If several servers of the same system areinstalled on the same host, one spool work process may run on a

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maximum of one of these servers.

o To summarize:

- The following theoretical minimum configurations result fromthe above information:for a central system: 5 DIA, 1 UPD, 0 UP2, 1 BTC, 1 ENQ, 1 SPOfor a dialog server: 2 DIA, 0 UPD, 0 UP2, 0 BTC, 0 ENQ, 0 SPO

How many work processes are useful?

o If there are too few processes of one type...... requests (dialog steps, updates, background jobs) must wait forfree work processes. Ideally, you should use a configuration inwhich at least one work process is always free. When you usetransaction SM50, you will see that the dialog work process withthe highest number uses almost no CPU time. (Equivalent: If someonewants to telephone from A to B, they do not want to wait.Therefore, the lines should never be 100% busy.)

o If too many processes are configured...... only swap space is consumed, and the system may become slightlyslower due to operating system paging. Therefore, if you havelimited main memory resources and the machine is heavily loaded, itmay make sense to use a relatively small number of processes.Dialog users or background jobs will then have to wait for freeprocesses, but that is less critical compared to the entire systemslowing down. For more information, see Note 9942.

o If the machine is very powerful...... it may make sense, to install several instances (see Note21960) or to change over to a 64-bit operating system (an evenbetter solution).

o Since the requirements for a server may vary, it often makes senseto define different operation modes for the entire system.Example: Daytime operation - many dialog processes; Nighttimeoperation - many background processesThe total number of work processes (DIA+UPD+UP2+BTC+ENQ+SPO) mustnot change during the switch; this applies to each server. Thenumber of spool processes (SPO) must also remain constant.

How do I see which work processes exist and what they do?

o Local:Tools -> Administration -> Monitor -> System Monitoring -> ProcessOverview (transaction SM50)

o Global:Tools -> Administration -> Monitor -> System Monitoring -> Servers-> <Double-click> (transaction SM51) or:Tools -> Administration -> Computing Center -> Management System ->Control -> All Work Processes (transaction SM66, the selection ofprocesses is adjustable)

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To see the utilization of the services (dialog, update), choose thefollowing: Transaction ST03 - > Performance Database -> Task Type Profile

System parameter setting:The number of work processes is initially predefined by the followingsystem parameters:

rdisp/wp_no_dia rdisp/wp_no_vb rdisp/wp_no_vb2 rdisp/wp_no_btc rdisp/wp_no_enq rdisp/wp_no_spo

By defining the operating modes, you can dynamically change thedistribution of work processes to services. The reservation of backgroundwork processes for job class A is also carried out exclusively by definingthe operation mode.

Online documentation is available for the system parameters (see Note31395).

Header Data

Release Status: Released for CustomerReleased on: 20.08.2010 08:10:53Master Language: GermanPriority: Recommendations/additional infoCategory: ConsultingPrimary Component: BC-CST Client/Server Technology

Secondary Components:BC-CCM-CNF-OPM Operation Modes

BC-CCM-CNF-PFL Profile Maintenance

BC-CST-DP Dispatcher, Task Handler

BC-CST-EQ Enqueue

BC-CST-UP Update

The Note is release-independent

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692646 Performance Content Integrator

351492 Setting up frontend printing as of Release 4.6B

186475 All update tasks are waiting with 'stopped CPIC' reason

108799 How many spool work processes for each instance?

36280 Background Work Processes Reserved for Job Class A

19706 Tuning the Spooler

9942 Maximum number of work processes

Documents

Note 39412 - How Many Work Processes Should Be Configured