Planning to review performance data

When establishing requirements and planning to monitor performance, you should also plan how to review the results of monitoring.

• Plan to review the performance data systematically. Review daily data weekly and weekly data monthly; review data more often when reports raise specific questions that require investigation.
  Depending on your system, the weekly review might require about an hour, particularly after you have had some experience with the process and are able to locate quickly any items that require special attention. The monthly review might take half a day at first, less time later on. But when new applications are installed, workload volumes increased, or terminals added, allow more time for review.
• Review the data on a gross level, looking for problem areas. Review details only if a problem arises or if you need to verify measurements.
• When reviewing performance data, try to identify the basic pattern in the workload, and then identify variations of the pattern. After a certain period, discard most of the data you have collected, but keep a representative sample. For example, save the report from the last week of a month for three months; at the end of the year, discard all but the last week of each quarter. Similarly, keep a representative selection of daily and monthly figures. Because of the potential volume of data, consider using Tivoli® Decision Support for z/OS, Application Monitor for z/OS, or a similar tool to track historical data in a manageable form.