Mean Time to Repair (MTTR) is the average time required to

• A. Reconfigure a failed component
• B. Restore a failed component or system to normal operation
• C. Detect a failure
• D. Prevent future failures

Answer: (B)

Downtime to recover from a failure is what MTTR measures. It represents the average time it takes to bring a failed component or system back to normal operation, counting the entire recovery process—from when the fault is identified through diagnosing, repairing, testing, and verifying that service is fully restored. This metric focuses on the repair and restoration phase, not on detecting the issue in the first place or preventing future faults. That’s why restoring to normal operation is the best description.

In practice, MTTR helps teams gauge how quickly a service can be recovered after an outage and where to focus improvement efforts, such as faster diagnostics, better repair processes, or more readily available spare parts.