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SAP Note 108799 - How many spool work processes for eachinstance?

 Note Language: English Version: 6 Validity: Valid Since 17.03.2000

Summary

Symptom 

As of Release 4.0A, you can configure more than one spool work process for

each instance. During the configuration of the R/3 server landscape, the

question arises as to how many spool work processes should be configured

for each server.

 Additional key words

Reservation of spool work processes, order processing in accordance with

the set sequence

Cause and prerequisites

SolutionThe spool work processes have different tasks: Up to (exclusively) 4.0A,

the spool work process is responsible for processing print requests and

transferring them to a host spool system. Furthermore it is responsible for

demanding the job statuses in the host spool systems and scanning the spool

database for requests lost through queue overflows. In Release 4.0A, it is

also in charge of reassigning output requests during a spool server

shutdown. In addition, a separate (printer-independent) link check for host

spool systems (access method U and S) is carried out in Release 4.0B.

As of Release 4.6A, a spool work process also conducts the deletion of

obsolete spool requests (as an option, you can configure this in

Transaction SPAD via spool-settings).

Thus, the tasks of a spool service can be divided into three classes:

o Processing of output requests

o Local management actions

- Requesting the host spool

- Link check

o Global management actions

- Scanning for lost requests

- Reassigning requests

- Deleting obsolete requests

The global management tasks are carried out throughout the system by a

maximum of one spool work process. In the case of several configured spool

work processes, the local management tasks are carried out for each

instance exclusively by one spool work process. As a result, the spool

service of an instance cannot be blocked by parallel processing of the same

management tasks. In this way the spool service cannot, for example, be

crippled by hanging or lengthy host spool demands if a minimum of two spoolwork processes is configured. Only the further demand is delayed until the

current demand process is completed.

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SAP Note 108799 - How many spool work processes for eachinstance?

due to different processing and process assignment times (through the

operating system) so that processing in accordance with a set sequence is

no longer possible. This is not always required. Therefore, as of Release

4.0A, you must decide separately for each R/3 output device whether

processing in accordance with a set sequence is required. When upgrading an

older system, this option is selected automatically to achieve compatible

behavior. New devices are created by default as not in accordance with a

set sequence.

Processing in accordance with the set sequence restricts the possibility to

carry out several processes in parallel. It can only be achieved if

processing is still carried out by a maximum of one spool work process.

When you process requests for output devices in accordance with a set

sequence, work processes are therefore exclusively reserved. This

reservation is carried out dynamically and does not need a separate

configuration.

Since requests can principally be dealt with by all work processes, a

separate incoming queue is used for every reserved spool work process. If a

spool work process receives a request for a device for which a work processhas already been reserved, this request is not edited by the further work

process, but simply put in its queue. If, on the other hand, no such

reserved spool work process exists, the current process is reserved for the

corresponding device and only processes its own input queue from this time

onwards. Only if all requests in this queue are processed, does it

participate again in the request dispatching and give up its reservation.

Due to the dynamic reservation it cannot happen that requests to (too many)

sequence devices cripple a spool server and that other requests can no

longer be processed since a once-reserved spool work process accepts no

more global requests until its internal queue is processed. However, at

this time its reservation is cancelled again so that it can also process

requests from other devices. If all spool work processes are reserved, no

more requests are distributed to the internal queues so that at least one

spool work process must give up its reservation before new requests can be

received.

Since the requests of a device which follow a set sequence can only be

processed by one spool work process, a performance bottleneck of a spool

server caused by an excessively high load cannot be solved by increasing

the number of the spool work processes.

The problem can only be solved by not adhering to the sequence. In the case

of devices which follow the sequence, only a performance bottleneck caused

by too many requests to different devices can be solved by increasing the

work process number.With the dynamic reservation, it is not necessary to increase the number of

spool work processes by changing the setting of the sequence.

Header Data

Release Status: Released for Customer

Released on: 16.03.2000 23:00:00

Master Language: German

Priority: Recommendations/additional info

Category: Consulting

Primary Component: BC-CCM-PRN-SPO Spool System

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SAP Note 108799 - How many spool work processes for eachinstance?

 Valid Releases

Software Component Release From  

Release

To

Release

and 

Subsequent

SAP_APPL 40 40A 40B XSAP_APPL 45 45A 45B X

SAP_APPL 46 46A 46B X

SAP_APPL 46C 46C 46C X

SAP_BASIS 46 46D 46D X

SAP_BASIS 60 610 640 X

SAP_BASIS 70 700 700 X

Related Notes

 Number Short Text

923610 Memory parameter recommendations for banking systems

351492 Setting up frontend printing as of Release 4.6B

65109 Long delays when printing during overload

39412 How many work processes should be configured?