Stochastic Models for Preventive Maintenance and Software Rejuvenation

Abstract

A number of stochastic models for preventive maintenance and specifically for software rejuvenation are presented and discussed in this chapter. Preventive maintenance is a method to enhance system reliability and availability. Even before a failure happens measures are taken to prevent system failure. Software rejuvenation is one such preventive action. Software rejuvenation restarts the process environment to counteract software aging. While the taken action is essentially the same as in the restart model the considered metrics are fundamentally different. In consequence, the developed models also differ from the restart model. While restart is exclusively carried out for the purpose of minimising task completion time and the system state is not considered, software rejuvenation models are in both aspects the opposite. Software rejuvenation models do not explicitly model the task completion time but instead focus on the operating environment processing the task. Software rejuvenation models minimise system downtime as well as the downtime costs not considering individual tasks. The restart model minimises task completion time while not explicitly considering possible system breakage.