Which metric describes the time to repair after a failure?

• A. The average time required to repair a failed component and restore service.
• B. The average time between successive failures.
• C. The time to first failure.
• D. The total uptime of the system.

Answer: (A)

MTTR, the mean time to repair, is the metric that describes the time it takes to repair after a failure. It represents the average duration from when a failure occurs to when the system is back in service, including diagnosing, repairing, testing, and restoring operation. This is why the choice describing the average time required to repair a failed component and restore service is the best fit. Other metrics cover different ideas: mean time between failures looks at the interval between failures, time to first failure measures how long until the first failure occurs, and total uptime measures how long the system runs before any downtime. MTTR directly reflects how quickly you can recover from a failure and thus influences overall system availability.