Reliability Monitor in Windows

Before you start

Objectives: Learn what is Reliability Monitor, why it is used, and how to run it.

Prerequisites: no prerequisites.

Key terms: Reliability Monitor, Windows, stability index, reliability


To maintain the reliability and performance of our Windows installation, we can take advantage of a Reliability Monitor tool. This tool will help us identify and solve performance and reliability problems that may come up. The Reliability Monitor is used to track a computer stability. It maintains historical data describing the operating system’s stability. It also provides detailed information that we can use to achieve optimal system reliability. The main advantage of Reliability Monitor is that it provides valuable information about system changes that were made before a problem occurred.

Intermittent problems are usually the most difficult to troubleshoot and fix. The Reliability Monitor is very hand tool to diagnose intermittent problems. The stability index based on the data collected over a lifetime of a system. To consider a computer stable, and award the maximum stability index of 10, a computer must have little to no reboots or failures. The minimum index value is 0. Keep in mind that stability index is not exact measure of reliability. Sometimes, installing a new software requires a reboot which initially lowers the index value, but ultimately makes the system more reliable than was before.

The Reliability Monitor provides a system stability chart, which provides an overview of system stability for the past year, in daily increments. This chart indicates warning and error messages, and it makes it easy to identify issues and the date on which the issue occurred. Each day in the stability chart is associated with a graph point, showing the stability index rating. The stability index is a weighted measure calculated on a number of failures seen over period of time. The index value is calculated on the data collected over the last 28 days, although we can display results over more days.

Recent failures are weighted more heavily than past failures, so that improvement over time is reflected in an increasing stability index, since reliability issues have been resolved. The stability index does not calculate the days in which the computer is turned off, or in sleep or hibernation mode. The dotted line on the graph indicates that there was not enough data to calculate the stability index. When enough data has been recorded, the line becomes solid.

If there are any changes to the system, an information icon appears on the graph for each day on which the system was altered. Reliability Monitor maintains up to a year of history for reliability and stability events. The stability chart displays a rolling graph organized by daily events.

Events that are tracked and monitored in the stability chart are:

  • Software installs or uninstalls
  • Application, hardware, Windows and other misc failures
  • Installations of OS patches, fixes and drivers
  • Memory, Hard Drive,  and driver failures

These are all tracked to help us identify the reasons for reliability issues. The rows in the lower half of the chart, track the events related to the reliability that either contribute to the stability of the system, or provide related information about software or driver installation. An icon appears in the column on the date that one or more reliability events are detected. An information icon indicates a successfull event such as a software install and uninstall. Warning icon indicates a failure. For all other reliability types an error icon indicates a failure.

To open Reliability Monitor from the command prompt, we can enter:

perfmon /rel