Spent half an hour sketching up Cognos process architecture — what goes where and when. Will refer to this drawing in my future hardware planning assigments 

Comments:

1. You can separate all components (Gateway, Application Server, Content Manager) into separate machines
2. There can be only one Content Manager service active in cluster at a time
3. There may be multiple gateway servers, as I was corrected. What I originally meant was close to something like ‘if you give user a cognos url, that url points to one specific gateway server’, so you have to do clustered web-server and application server installation for gateway fault-tolerance.
4. There may be multiple active dispatchers in cluster
5. Each dispatcher consists of multiple services, that may be turned off or on for a specific server in cluster.
6. Most dispatcher services are processed in application server (Tomcat by default and almost any other of your choice), which can use either 32 or 64 bit java machine
7. Reports (interactive and batch) are processed by a special process ‘BIBus’, which is a C++ 32 bit application (hence the 2Gb cap for each process and CCLOutOfMemory errors). Number of such processes depends on Dispatcher service settings, load on each process depends on affinity connection settings.
8. BIBus processes generate temporary files if they require significant amount of local processing (hence UDA files problems)
9. Each BIBus process can occupy up to 2Gb RAM and 1 CPU Core

Basic rules for capacity planning I use (your mileage may vary greatly, it depends on reports design, size and calculation complexity in first hand):

1. Estimate number of concurrent users
2. There should be a BIBus process for each couple concurrent users
3. There should be at least 1 or 2 cores for all other dispatcher services
4. There should be at least 1-2 Gb of RAM for Application Server
5. There should be at least 2-3 Gb for Operation System (it depends on operation system greatly)
6. There should be a separate database instance for Content Store and Audit database

For example, if we’re talking about 20 concurrent users (mind that it’s 2000 named users by basic IBM metrics), we’ll need:

• 10 BIBus processes, each will take 1 Core and 2 GB Ram
• 2 cores and 2 Gb ram for dispatcher and application server (for each dispatcher server, if there going to be a cluster environment)
• 3 Gb for operating system (for each dispatcher server, if there going to be a cluster environment)

And it gives us 16 cores, 32 Gb RAM for a single server.

Suggested reading:

– Architecture and Deployment Guide )

– these threads on DeveloperWorks, where Phil W. describes all this way better than I’ll ever do:

http://www.ibm.com/developerworks/forums/thread.jspa?messageID=14233120