Monitoring with Performance Counters

  • Article

Applies To: Windows Server 2003, Windows Server 2003 with SP1

Both System Monitor and Performance Logs and Alerts allow you to examine the output of performance counters, which monitor the activity of specific performance objects. Each performance counter is named for the object for which it collects data and the type of data that it collects. For example, the Processor\% ProcessorTime counter is the primary indicator of processor activity, displaying the average percentage of busy time observed during the sample interval.

A performance object often offers a choice of more than one instance. Using the Processor object as an example, if you are monitoring a dual-processor computer, the first processor instance is 0 and the second processor instance is 1. A commonly used instance is the _Total instance, which monitors the sum of the values of a specific counter's instances.

Components of a counter path

The counter path contains the computer name, and the performance object, instance, and counter.It is typically represented in the following way:

\\ComputerName\Object(Instance)\Counter

The computer name is optional. If you do not designate a computer name, the counter monitors the local computer.

Again, using the Processor object as an example, if you want to monitor the percentage of processor time that your #0 processor uses, your selection is represented in the following way:

Processor (#0)\% ProcessorTime

Sampling methods for counters

Performance counters collect and display their data in one of two ways:

  • Instantaneous counters. These counters display the most recent measurement of an aspect of resource use. For example, the Process\Thread Count counter shows the number of threads for a particular process as of the last time it was measured. An instantaneous counter might have a name containing the word Current. Unless the server has a steady workload, these counters might not provide meaningful data.

  • Averaging counters. Based on the previous two measurements, averaging counters derive an average value for the interval between the measurements. These counters typically calculate a percentage or the number of occurrences per second. For example, the Memory\Pages/sec counter shows the number of memory pages read over the sample interval, divided by the number of seconds in the interval. When you start one of these counters, no value is displayed until the second measurement is taken.