Configuring session ratios

Several factors affect how many sessions are needed. Administrators configure session ratios on the Server tab on the System Administration dialog box.

About this task

Use these guidelines to configure IBM® Rational® Change. For the best results, start with these figures and refine them through experimentation.
Table 1. Guidelines for configuring IBM Rational Change
Number of active users Minimum and maximum sessions Session ratio
1 - 15 2 - 5 4
15 - 50 4 - 10 5
50 - 100 6 - 13 8
100 - 200 8 - 20 10
200+ 10+ 10 - 20

Under some circumstances, all sessions in the session pool might be busy and unavailable for new requests. In particular, when you run many reports, back-end sessions run more slowly, which prevents other requests from being completed. When session pools are busy, the user receives this message:

Failed to get a session: Exceeded retry limit.

This message indicates that there is a server configuration issue.

To alleviate this problem, try one or more of these solutions:
  • Increase the minimum number of sessions.
  • Decrease the users per session ratio.
  • Increase the number of attempts for a request.
  • Periodically check the size of the web server process.

    Under normal usage patterns, the delivered software has a maximum heap size setting sufficient to support about 200 active users, each making a request every 5 - 10 minutes. If the web server process exceeds this threshold, performance might degrade. To resolve this issue, change that threshold to a more appropriate number, based on experimentation.


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