Analysis of conditional MTTF of fault-tolerant systems

Mean time to failure (MTTF) is one of the most frequently used dependability measures in practice. By convention, MTTF is the expected time for a system to reach any one of the failure states. For some systems, however, the mean time to absorb to a subset of the failure states is of interest. Therefore, the concept of conditional MTTF may well be useful. In this paper, we formalize the definition of conditional MTTF and cumulative conditional MTTF with an efficient computation method in a finite state space Markov model. Analysis of a fault-tolerant disk array system and a fault-tolerant software structure are given to illustrate application of the conditional MTTF. © 1998 Published by Elsevier Science Ltd. All rights reserved.