What do MTBF and MTTR measure, and how are they used?

What do MTBF and MTTR measure, and how are they used?

• A. MTBF measures time to repair; MTTR measures time between failures.
• B. MTBF measures cost per failure.
• C. MTBF measures average time between failures; MTTR measures time to repair; both gauge reliability and maintainability.
• D. MTBF measures user satisfaction.

Answer: (C)

MTBF and MTTR are reliability and maintainability metrics that describe how a system behaves in operation and after failures. MTBF, or mean time between failures, measures the average time the system runs before a failure occurs. MTTR, or mean time to repair, measures the average time it takes to diagnose, repair, and restore the system after a failure. Together they show how often failures happen and how quickly you can recover, which informs maintenance planning, spare-part inventory, and scheduling. They also relate to overall availability, roughly calculated as MTBF divided by (MTBF plus MTTR). For example, if MTBF is 100 hours and MTTR is 5 hours, availability is about 95%. Note that MTBF applies to repairable systems during operation, while MTTR focuses on the repair time after a failure.

MTBF and MTTR are reliability and maintainability metrics that describe how a system behaves in operation and after failures. MTBF, or mean time between failures, measures the average time the system runs before a failure occurs. MTTR, or mean time to repair, measures the average time it takes to diagnose, repair, and restore the system after a failure. Together they show how often failures happen and how quickly you can recover, which informs maintenance planning, spare-part inventory, and scheduling. They also relate to overall availability, roughly calculated as MTBF divided by (MTBF plus MTTR). For example, if MTBF is 100 hours and MTTR is 5 hours, availability is about 95%. Note that MTBF applies to repairable systems during operation, while MTTR focuses on the repair time after a failure.