What is Availability?

Definitions

1. The percentage of time that a service or resource is up.
2. The percentage of time that a service or resource is available when it is expected to be available such as during business hours.
3. The actual uptime of a resource as a percentage of its expected uptime.
4. The uptime of a facility, infrastructure component, machine, device, service, product, function, system, business capability or process.

Notes

1. It is common for availability to be calculated relative to 24/7/365 uptime. For example, an IT service with availability of 99.99% is down for less than 5 minutes a month.
2. Services and resources that are only expected to be up during certain business hours are calculated against this business schedule.
3. Some industries commonly exclude planned maintenance schedules from availability calculations.

Quality