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Reliability Metrics · MTBF

Mean time between failures

Mean time between failures is the average time from one failure to the next for a system.

What is mean time between failures?

Mean time between failures describes the average time from one failure to the next for a system. In reliability work, the label is useful only when it maps to a measurable check, a clear owner, and a next action when expectations break. Without that operational meaning, the phrase becomes decoration in dashboards and status updates.

Why it matters

Mean time between failures matters because teams need a precise shared meaning for the average time from one failure to the next for a system. Vague language turns incidents into arguments about words instead of fixes.

When everyone uses the same definition, alerts, status updates, and post-incident reviews stay aligned.

How it works

In practice, the average time from one failure to the next for a system shows up as a concrete signal you can measure or communicate. Operators define what good looks like, watch for deviations, and record what happened when expectations break.

The useful version of mean time between failures is operational: it changes who gets notified, what customers see, or which metric a team reviews after an incident.

Practical example

Imagine a team operating around MTBF measured across production incidents. When observed behavior stops matching the definition of mean time between failures, the team treats that change as a reliability event with a clear owner and next step.

Common misconception

MTBF proves a system will never fail again

That reading usually collapses distinct ideas into one slogan. Keep mean time between failures tied to observable behavior so the definition stays useful under pressure.

How Fajita handles this

MTBF is a reliability statistic, not a promise. Sample size matters.

MTBF

MTBF = Total operating time ÷ Number of failures
  • Define operating time carefully.
  • Small samples produce misleading averages.

Related documentation

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