Monitoring
Mean Time Between Failures
MTBF
Mean Time Between Failures (MTBF) is the average time a system operates between one incident and the next. MTBF measures how reliable something is; MTTR measures how quickly you recover. Together they define uptime: uptime = MTBF / (MTBF + MTTR).
In depth
MTBF is calculated over a fixed window (usually 30-90 days) by dividing total uptime by the number of incidents. A service with 720 hours of uptime and 4 incidents has an MTBF of 180 hours.
MTBF is the reliability lever engineering owns most directly: better testing, staged rollouts, redundant infrastructure, capacity planning. MTTR is the response lever ops owns: paging, runbooks, automated remediation.
Why it matters
Uptime targets are hit by pushing MTBF up or MTTR down. If your MTTR is already tight, pushing MTBF is the only lever left — that means fewer risky deploys, better tests, and change-freeze windows around peak traffic.
Related terms
MTTR
Mean Time To Recovery (MTTR) measures the average time it takes to restore service after an incident begins. I…
Uptime
Uptime is the percentage of time a website or service is reachable and serving correct responses. It is the he…
SLA
A service level agreement (SLA) is a contractual commitment between a provider and a customer specifying a mea…
Incident
An incident is a confirmed period of degraded or unavailable service that requires human attention. Incidents …
Recovery Point Objective
Recovery Point Objective (RPO) is the maximum amount of data loss (measured in time) a business can tolerate a…
Browse the full Lemwatch monitoring glossary (47 terms).