Measuring the baseline

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Performance problems are often reported immediately following some change to system hardware or software. Unless there is a pre-change baseline measurement with which to compare post-change performance, it can be difficult to qualify the problem.

About this task

Any change in the environment, including software, hardware, or network changes, can affect the performance of operations in your environment.

As a best practice, monitor the environment before and after each change. The alternative is to take the baseline measurements at regular intervals, for example, once a month, and save the output. When a problem is found, you can use the previous measurements for comparison. It is a good idea to collect a series of measurements, which can help you diagnose a possible performance problem.

To maximize performance diagnosis, collect data for various periods of the day, week, or month when performance is likely to be an issue. For example, you might have workload peaks during these times:
  • In the middle of the mornings for online users
  • During a late-night batch run
  • During the end-of-month processing
  • During major data loads
Collect data for each peak in workload because a performance problem might cause problems only during one of these periods and not during other times.
Restriction: Using any tool to collect the baseline data can impact the performance of the system that is being measured.

Procedure

To collect baseline data, you can use the following tools:
  • On any operating system, you can use the IBM Storage Protect servermon component. The servermon component is automatically installed and configured as part of the server installation to collect data at regular intervals.
  • On AIX® and Linux® operating systems, you can use the nmon utility.
  • On Windows operating systems, you can use the perfmon utility to gather a set of performance counters.

Periodically record your baseline measurements so that you can use the data for comparisons after an unexpected performance degradation. If you collect baseline data before a performance problem is detected, IBM® Support can use the data to help you resolve performance problems.