About high availability

High Availability refers to the availability of resources in a computer system following the failure or shutdown of one or more components of that system.

At one end of the spectrum, traditional HA has been achieved through custom-designed and redundant hardware. This solution produces High Availability, but has proven to be very expensive.

At the other end of the spectrum are software solutions designed to function with off-the-shelf hardware. This type of solution typically results in significant cost reduction, and has proven to survive single points of failure in the system.