Reliability (ITILv3):    [Service Design] [Continual Service Improvement] A measure of how long a Configuration Item or IT Service can perform its agreed Function without interruption. Usually measured as MTBF or MTBSI. The term Reliability can also be used to state how likely it is that a Process, Function, etc., will deliver its required outputs.

See also: Availability

Reliability (ITILv2):    The ability of a component or IT service to perform a required function under stated conditions for a stated period of time. Reliability is now often taken to include resilience.

See also: MTBF

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