Tuning the system

Specifically, these changes to parameters allow IMS to:

• Attain performance criteria
• Efficiently use resources

Collecting and interpreting IMS monitoring data explains setting up performance objectives and monitoring, which are prerequisites to tuning activities for the IMS online system. Terms defined in that section are not generally explained again. Your data for analysis probably depends on the reporting capabilities of one or more of the following tools:

• The Log Transaction Analysis utility (DFSILTA0)
• The Statistical Analysis utility (DFSISTS0)
• The IMS Monitor
• Report programs executing under GPAR: IMSASAP II
• Resource Monitoring Facility (RMF™ II)

This section presents a general strategy for tuning the IMS online system. After some explanation of performance management, the topics in this section approach tuning in two stages:

• Initializing z/OS® and IMS parameters
• Identifying and correcting performance problems

For each activity, several major areas of concern are identified. You should examine the potential tuning activities in each area. This is an outline strategy and not a substitute for more formal performance studies. However, this information should prepare you to address most major problems.

Tuning the system involves initializing z/OS and subsystem parameters and identifying and correcting problems as they relate to tuning. These two topics can be characterized as guidance to reduce the chance of initial problems and a methodology for ongoing problem resolution. However, you should begin by understanding how they relate to the other aspects of the performance management process.

Tuning actions and system redefinition are two aspects of IMS performance management that are part of a continuous cycle of activities, as illustrated in the following figure. Interpreting system performance includes both design decisions and prediction.