On relationship between the number of debuggings and operational software availability measurement under intermittent use

摘要

This paper discusses the software availability modeling when the system is used intermittently. From the viewpoint of users, the occurrence of a system failure is recognized when the event either that a software failure occurs when the system is in use or that a usage demand occurs when the system is under restoration arises. Here we derive three new measures for software availability assessment; the disappointment probabilities in use, due to demand rejection, and under restoration. We consider two kind of restoration actions during the operation phase; one involves debuggings and the other does not involve debuggings. The time-dependent behavior of the system alternating between up and down states is described by a Markov process. Then we incorporate the software reliability growth process, the upward tendency in difficulty of debugging, and the imperfect debugging environment into the model. Finally, we show several numerical examples of software availability analysis.