Mean Time Between Failure (MTBF) is a reliability term used to provide the amount of failures per million hours for a product. MTBF may be an expected line item in an RFQ (Request For Quote). MTBF becomes very important when hosting mission critical applications. MTBF is used for both repairable and non-repairable items.
Mean Time To Repair (MTTR) is the time needed to repair a failed hardware module. In an operational system, repair generally means replacing a failed hardware part. Here MTTR could be viewed as mean time to replace a failed hardware module.
Mean Time To Failure (MTTF) is a basic measure of reliability for non-repairable systems. It is the mean time expected until the first failure of a piece of equipment. MTTF should be used for non-repairable items.
Failure In Time (FIT) is another way of reporting MTBF. FIT reports the number of expected failures per one billion hours of operation for a device.
RoHS (Restriction of Hazardous Substances)
RTB (Run The Business)
MTBF = 1 FR1 + FR2 + FR3 + ………..FRn
where FR is the failure rate of each component of the system up to n components