MARKOVIAN SOFTWARE AVAILABILITY MEASUREMENT FOR CONTINUOUS USE

摘要

Software availability models proposed so fax often provide quantitative measures taking notice of whether or not the software system is available at a given time point. This paper proposes software availability measures on the supposition that customers use the system continuously. 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 given 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 upwardness of difficulty in restoring are also considered. Numerical examples of these measures are presented.