When either an elastic infrastructure or platform is offered by a provider, service availability is defined by the conditions that must be fulfilled by the offering and the time-frame within which service availability is assured. These two factors enable the computation of hosted application availability. With node-based availability, the service provider guarantees the availability of each application component.
Available is generally defined as being reachable and capable of performing its advertised function. This availability time-frame is expressed as a percentage. As an example, an availability of 99.95% means that a component will be available 99.95% of the time. The following figure depicts this example:
