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:
“As I walked on the glacis I heard the sound of a bagpipe from the soldiers’ dwellings in the rock, and was further soothed and affected by the sight of a soldier’s cat walking up a cleated plank in a high loophole designed for mus-catry, as serene as Wisdom herself, and with a gracefully waving motion of her tail, as if her ways were ways of pleasantness and all her paths were peace.”
—Henry David Thoreau (1817–1862)
“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)