MTTR

MTTR stands for Mean Time To Repair, though some contexts use Mean Time To Recovery. It is a reliability and maintenance metric that measures the average time required to restore a system or service after a failure. MTTR is commonly used to assess maintainability, incident response, and the effectiveness of repair processes.

Calculation and scope can vary by organization. A typical calculation is MTTR = total downtime due to incidents in a period divided by the number of incidents, with units expressed in minutes or hours. Some definitions measure from the moment an incident is detected to the moment service is fully restored; others focus on the actual repair duration, excluding detection and recovery activities. Clear, consistent definitions are important for comparability.

MTTR is related to, but distinct from, other reliability metrics. MTBF (mean time between failures) measures system reliability and failure frequency, while MTTD (mean time to detect) and MTTA (mean time to acknowledge) pertain to detection and notification. MTTR can be influenced by factors such as system complexity, the availability of skilled personnel, spare parts, tools, automation, runbooks, and vendor dependencies. High MTTR often signals opportunities in incident management, diagnostics, change management, and preventive maintenance.

Best practices to reduce MTTR include establishing clear incident management processes, maintaining up-to-date runbooks and playbooks, improving monitoring and early detection, ensuring rapid access to spare parts and skilled staff, conducting regular drills, and performing root cause analysis to implement permanent fixes. Used responsibly, MTTR helps organizations gauge and improve resilience, while setting realistic targets aligned with service level expectations.