Availability and Cost Analysis of a Fault-Tolerant Software System with Rejuvenation

In recent years, remarkable attention has been paid to software aging phenomena, in which the performance of software systems degrades with time. Software aging may eventually leads to transient crash/hang failures. The well-known technique of software rejuvenation can be regarded as the most effective procedure to counteract the aging phenomena. In this paper, the concept of common software-aging-related faults in fault-tolerant systems is proposed. Then the common faults defined are integrated into a behavior model of a double-version fault-tolerant software system. The dependability measures, such as availability, cost, and the availability to cost ratio, are evaluated as bivariate functions using continuous time Markov chain (CTMC). Finally, the effects of common software-aging-related faults are investigated based on several numerical examples.