• Reliability Modelling of a Computer System with Independent H/W and S/W Failures Subject to Maximum Operation and Repair Times

Abstract

In this paper, some reliability measures of a computer system of two cold standby identical units having hardware and software components are obtained using semi- Markov process and regenerative point technique. For this purpose, a reliability model is developed considering independent h/w and s/w failures. There is a single server who visits the system immediately to do preventive maintenance, repair and replacement of the components upon their failures. The unit undergoes for preventive maintenance after a maximum operation time at normal mode. If repair of the component is not possible up to a pre-specific time (called Maximum Repair Time), the components are replaced by new one with some replacement time. However, only replacement of the software components by new one is made after failures. The failure time of the components follow negative exponential distribution while the distributions of preventive maintenance, repair and replacement time are taken as arbitrary with different probability density functions. The graphical behaviour of the results has also been shown for a particular case to improve the importance of the study.