Establishing monitoring activities and techniques

Establishing an ongoing strategy involving monitoring activities and monitoring techniques provides an understanding of your CICS® production system that helps to ensure optimum performance and avoid unexpected problems.

Monitoring is used to describe regular checking of the performance of a CICS production system, against objectives, by the collection and interpretation of data. Analysis describes the techniques used to investigate the reasons for performance deterioration. Tuning can be used for any actions that result from this analysis.

Monitoring is an ongoing activity for a number of reasons:
  • It can establish transaction profiles (that is, workload and volumes) and statistical data for predicting system capacities
  • It can give early warning through comparative data to avoid performance problems
  • It can measure and validate any tuning you might have done in response to an earlier performance problem.

A performance history database (see IBM Z Decision Support for an example) is a valuable source from which to answer questions on system performance, and to plan further tuning.

Monitoring can be described in terms of strategies, procedures, and tasks.

Strategies include these elements:
  • Continuous or periodic summaries of the workload. You can track all transactions or selected representatives.
  • Snapshots at normal or peak loads. Monitor peak loads for these reasons:
    • Constraints and slow responses are more pronounced at peak volumes.
    • The current peak load is a good indicator of the future average load.

Procedures, such as good documentation practices, provide a management link between monitoring strategies and tasks.

Tasks (not to be confused with the task component of a CICS transaction) include:

Allocate responsibility for these tasks between operations personnel, programming personnel, and analysts. Identify the resources that are to be regarded as critical, and set up a procedure to highlight any trends in the use of these resources.

Because the tools require resources, they can disturb the performance of a production system.

Give emphasis to peak periods of activity, for both the new application and the system as a whole. Run the tools more frequently at first if required to confirm that the expected peaks correspond with the actual ones.

It is often not practical to keep all the detailed output. File summarized reports with the corresponding CICS statistics, and hold output from the tools for an agreed period, with customary safeguards for its protection.

Do not base conclusions on one or two snapshots of system performance, but rather on data collected at different times over a prolonged period. Emphasise peak loading. Because different tools use different measurement criteria, early measurements might give apparently discrepant results.

Plan your monitoring procedures ahead of time. In your procedures, explain the tools to be used, the analysis techniques to be used, the operational extent of those activities, and how often they are to be performed.

Developing monitoring activities and techniques

To collect and analyze data that is consistent with your strategy, you must have the correct tools and processes in place. When you are developing a main plan for monitoring and performance analysis, consider these points:
  • Establish a main schedule of monitoring activity. Coordinate monitoring with operations procedures to allow for feedback of online events and instructions for daily or periodic data gathering.
  • Consider your business in relation to system performance, for example, what will be the growth of transaction rates and changes in the use of applications and future trends. Consider the effects of nonperformance system problems such as application abends, frequent problems, and excessive attempts.
  • Decide on the tools to be used for monitoring. The tools used for data gathering must provide for dynamic monitoring, daily collection of statistics, and more detailed monitoring. See Planning your monitoring schedule for more information.
  • Consider the kinds of analysis to be performed. Take into account any controls you have already established for managing the installation. Document what data is to be extracted from the monitoring output, identifying the source and usage of the data. Although the formatted reports provided by the monitoring tools help to organize the volume of data, design worksheets to assist in data extraction and reduction.
  • Compose a list of the personnel who are to be included in any review of the findings. The results and conclusions from analyzing monitor data should be shared with the user liaison group and system performance specialists.
  • Create a strategy for implementing changes to the CICS system design resulting from tuning recommendations. Incorporate the recommendations into installation management procedures, and include items such as standards for testing and the permitted frequency of changes to the production environment.

Planning the performance review process

A plan of the performance review process includes a checklist of the tools and analysis that are required to implement monitoring procedures. Establish a simple schedule for monitoring procedures. To create a performance review process, perform the following tasks:
  • List the CICS requests made by each type of task. This helps you decide which requests or which resources (the high-frequency or high-cost ones) need to be looked at in statistics and CICS monitoring facility reports.
  • Create a checklist of review questions.
  • Estimate resource usage and system loading for new applications. This is to enable you to set an initial basis from which to start comparisons.