What Causes Outages?

According to a study by the Gartner Group in 1999 (whose results are born out by the author’s experience), the causes of outages can be allocated into three basic categories:

40% People. This includes operator error, malicious activities, and deliberate outages for maintenance.

40% Applications. This includes both custom and commercial applications directly involved in providing a service to the user.

20% Infrastructure. This includes all other elements required to provide service to the user, including power systems, network infrastructure (excluding the Internet), server hardware, operating systems, and support services such as DNS.

Although they have potential for enormous business impact, the contribution to downtime caused by disasters such fires, floods, earthquakes, or bombs are too miniscule to measure.

Even if an organization addresses infrastructure with reliable and redundant hardware and system software, it has little chance of greatly increasing availability unless it adequately addresses application and people issues.