What Is High Availability?

High availability is a system design protocol and associated implementation that ensures a certain absolute degree of operational continuity during a given measurement period. Availability refers to the ability of the user community to access the system, whether to submit new work, update or alter existing work, or collect the results of previous work. If a user cannot access the system, it is said to be unavailable. Generally, the term downtime used to refer to periods when a system is unavailable. High Availability, or HA as it is abbreviated, refers to the availability of resources in a computer system, in the wake of component failures in the system.