Configuration size in Cognos Configuration

[terry_stjean]

In Cognos Configuration (V8), in the Resource Properties, you can set it for either a small, medium or large configuration.
How do you determine which configuration you should use.
I don't see anything in the manual regarding this?

Terry

[COGNOiSe administrator]

Since the only thing they control is RAM for CM, none in particular. Use common sense. If you have 1GB of free RAM available, don't set it above 768.

[terry_stjean]

Thank your for your reply.
We have 3.5 GB memory on the server with a little over 2 GB free.
The current configuration is set to a small configuration with Maximum memory set to 768.
Should I delete the small configuration and create a new medium or large configuration or just change the Maximum memory to say 2 GB.

Terry

[COGNOiSe administrator]

No, the preferred size for Cognos 8 CM on Windows is 768-1024, not exceeeding 1280MB. You don't have to delete the existing configuration. You may just change the VM size. Keep in mind, that on top of the CM VM, every report processor will consume anywhere from 200MB to 1GB of RAM when creating reports. The average maximum I saw is 500MB per process.

[kommireddy]

KB#1022448.2 might answer some of your questions,

The minimum amount of RAM required to operate ReportNet is 1GB, and 2GB for Cognos 8 (as specified under the System Requirements section of the Installation and Configuration Guide).  Moreover, this is assuming there are no other applications or servers competing for system resources.

There is also a limitation on how much total memory ReportNet or Cognos 8 can utilise per process...

Cognos 8 and ReportNet run primarily in a Java environment (you may elect to run multiple Java instances on a single host to support larger deployment requirements) and each Java process may not exceed 2GB of memory.

The second main component is the report running process called BIBusTKServerMain. We specify how many of these
processes may exist at any one time via the Server Administration page of the Cognos Connection portal and likewise, these
processes may not exceed 2GB of RAM.

As Java and BIBusTKServerMain are 32-bit applications they are only capable of using up to 2GB of memory per process.

[sir_jeroen]

Maybe this can clarify it:

By setting the amount of memory you set the heap size to 768MB.

Definition of heap size:
 

The heap is the area of memory in which the Java Virtual Machine (JVM) allocates new Java objects; the fast majority of the JVM's memory
  usage is its heap.

You might notice that the java.exe process can take up over 768MB that's because the Java.exe process consists of the following 3 parts: JAVA + HEAP + JNI

BiBusTkServerMain processes are the Report Service and Batch ReportService and are configured within Cognos Connection -> Server Administration. Depending on the Windows OS version (Only Windows 2003 Enterprise can address up to 2GB PER PROCESS) they can address up to 2GB. For tuning these processes take a look in the  "Proven Practices" section on http://support.cognos.com

For more information you can find some documentation in the proven practices under "performance" eg. http://support.cognos.com/supported/tti/public/docs/cognos_pp_performance_java_garbage_collection.pdf?lid=cognos_pp_performance_java_garbage_collection