Chapter 12. Collecting Useful Data

Your performance test is only as good as the data it produces. We often find customers with excellent performance tests in place but no clear plan for gathering data. Without good data from each test run, you cannot know if the changes you make between runs have the desired impact on your site's performance.

In our experience, customers either capture too much or too little data during their test runs. Not surprisingly, a large, multi-tiered web site generates lots of data. Some customers capture so much data that they actually impact the performance of the test environment. Excessive data logging and data capture often take away significant resources from the test systems. At the other extreme, some customers fail to capture even the most fundamental data points for each run.