The Concept of Coverage and Its Effect on the Reliability Model of a Repairable System

Duplication is a technique frequently employed to achieve high reliability for a repairable system. Although the philosophy of duplication is that it takes two faults to place a system out of service, there are generally some critical single faults that cause a system failure. This paper considers the effect of such a set of faults on a repairable system's reliability. It is shown that even a small number of such faults may severely degrade the mean time to system failure and the expected downtime for an otherwise highly reliable system.