抄録
Most of software availability models so far have paid attention to whether or not the software system is available only at a given time point. This paper discusses software availability measurement considering continuous use. In particular, the following two measures are derived: the interval software reliability defined as the probability that the system is continuously available for a given time period, and the conditional mean available time defined as the mean operable time measured from a time point at which the system is operating. The stochastic behavior of the system alternating between up and down states is described by a Markov process. Then, the software reliability growth process and the upward tendency of difficulty in debugging are also incorporated in the model. Finally, we show numerical examples of software availability analysis.
