Fundamentals
MTBF / MTTR
Mean time between failures and mean time to recovery. Availability = MTBF / (MTBF + MTTR).
Why interviewers ask about it
MTTR is usually the cheaper lever. A system failing weekly but recovering in 20 seconds beats one failing yearly and taking six hours.
Related terms
This term is part of the free System Design interview preparation module - browse the full glossary for every definition.