Performance Monitor (perfmon) is the preferred tool to measure the performance of Windows systems. The perfmon tool provides an analysis view with a chart and metrics of the Last, Average, Minimum, and Maximum values.
There are scenarios where the line in the chart is the most valuable piece of information, such as a
memory leak. Other times we may not be looking for a trend, the Last, Average, Minimum, and Maximum metrics may be valuable. One example where the metrics are valuable is when evaluating average disk latency over a period of time. In this article we are going to use disk latency counters to illustrate how metrics are calculated for performance counters. The concepts we will illustrate with disk latency apply to all performance counters. This article will not be a deep dive into understanding disk latency, there are already many sources of information on that topic.
