availability

availability

Definition: (ITIL Service Design) Ability of an IT service
or other configuration item to perform its
agreed function when required. Availability is
determined by reliability, maintainability,
serviceability, performance and security.
Availability is usually calculated as a
percentage. This calculation is often based
on agreed service time and downtime. It is
best practice to calculate availability of an IT
service using measurements of the business
output.