Chapter 9: Perfmon

Overview

WINDOWS PERFORMANCE MONITOR (Perfmon) is a logging application distributed with the NT operating system (NT 3.1 and above) that allows users to log and monitor various aspects of their system. The Perfmon application (the front-end utility, not the underlying system) is designed for short- term , real-time monitoring of a system. The data is exposed as counters and graphs and may be viewed either locally or remotely.

Perfmon also provides a logging mechanism that enables users to collect data in a log file that they can export and view (as graphs or histograms) using the System Monitor. The logging mechanism is designed for extended monitoring of local or remote systems (or both).

The system is designed so you can determine how often to log data and how many counters to log. It even enables you to have multiple machines record data to a single log file (on a single administrator system) to enable easier maintenance of multiple machines (e.g., a Web farm). It s important to remember that excessive logging may lead to system slowdown and increased overhead for using logs and alerts. Excessive logging to a single system may also cause extensive network traffic.

The operating system provides a large number of base counters that are useful for monitoring generic system usage. These include counters that can be enabled for logging memory, processors, disks, and the network, among others. Many other applications, such as IIS, Exchange Server, and SQL Server, install additional counters that allow users to monitor application-specific functionality.

You can easily store Perfmon data in a database, which allows for long-term storage and backup of data, as well as the ability to make extensive and complex queries on the logged information. Perfmon is a stable system with a well-documented interface, so many tools are available to collect and analyze the data it stores.

Because many features, such as remote access, central logging, and graph and histogram generation are provided for free, Perfmon has several benefits over custom logging systems.

In the case of Web applications and ATL Server, you can use Perfmon to store and display information about your Web site. This information includes commonly used statistics such as the number of hits, bytes downloaded, pages visited, and so on.

Although Perfmon is perfectly suited to this task, it s also suitable for the realtime monitoring of any information on your system. You can use the ATL Server Perfmon helper classes for a wide variety of tasks , such as gathering and storing data from a remote sensor (in any sort of application, including non-Web applications).