Chapter 8: High Availability

Failover clusters typically protect against hardware failure. Overall system failures (times of system unavailability) often aren’t the result of server failures but are more commonly caused by power outages, network stoppages, security issues, or misconfiguration. A redundant server generally won’t protect against an unplanned outage such as lightning striking a power substation, a backhoe cutting a data link, an administrator inadvertently deleting a machine or service account, or the misapplication of a zoning update in a Fibre Channel SAN fabric.

Failover clustering protects against certain hardware failures but against few of the typical causes of system instability or unavailability. With that being said, many organizations look to failover clustering to improve system availability.