High availability is a system design approach and associated service implementation that ensures a prearranged level of operational performance will be met during a contractual measurement period.
Users want their systems, for example wrist watches, hospitals, airplanes or computers, to be ready to serve them at all times. 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 is used to refer to periods when a system is unavailable.
Read more about High Availability: Scheduled and Unscheduled Downtime, Percentage Calculation, Measurement and Interpretation, Closely Related Concepts, System Design For High Availability, Reasons For Unavailability, Costs of Unavailability
Famous quotes containing the words high and/or availability:
“Tragedy is always a mistake; and the loneliness of the deepest thinker, the widest lover, ceases to be pathetic to us so soon as the sun is high enough above the mountains.”
—Margaret Fuller (1810–1850)
“Since ... six weeks ago, there has been no day in which I have not had letters and visits on the subject of my nomination for the Presidency.... I say very little. I have in no instance encouraged any one to work to that end.... I have said the whole talk about me is on the score of availability. Let availability do the work then.”
—Rutherford Birchard Hayes (1822–1893)