Final answer:
A metric of how frequently a service or other configuration item fails is called reliability. Reliability can be measured using metrics such as mean time between failures (MTBF) and failure rate.
Step-by-step explanation:
A metric of how frequently a service or other configuration item fails is called reliability. Reliability is a measure of the probability that a system will perform its intended function without failure over a specified period of time.
One common metric used to measure reliability is the mean time between failures (MTBF). MTBF is the average time that elapses between failures of a system or component. A higher MTBF indicates a higher level of reliability.
Another metric that is often used is the failure rate. The failure rate represents the probability that a system will fail within a given time period. A lower failure rate indicates a higher level of reliability.