Reliability modeling and economic analysis of computer systems with hardware and software failures

Abstract

The complexity, interdependences and rapidity of the events in modern society have accelerated demands for more effective ways to store, process and manage information. Advantages of both computer hardware and software have provided the technology that can make it possible to effectively address many of these demands. Today s computers are highly versatile tools across a myriad disciplines and usages. They can perform varied tasks, from correspondence to maintain inventory information to creating drawing and illustrations and many more. A breakdown of computer base systems may be costly, dangerous and make cause confusion in our society. It is, therefore, of great importance to operate such systems with high reliability. Inspite of increasing development and availability of new computer technologies, a little work has been dedicated to the reliability modeling of computer systems with independent failure of h/w and s/w components. Hence, in the present thesis entitled Reliability Modeling and Economic Analysis of Computer Systems with Hardware and Software Failures some reliability models of a computer system of two identical units are analysed stochastically in detaile introducing the concepts of independent failure of h/w and s/w components, repair of h/w components subject to inspection, replacement of s/w components instead of repair and priority to replacement of the h/w and s/w components over repair activities of each other. The expressions for several reliability and economic measures of the system models such as transition probabilities, mean sojourn times, mean time to system failure (MTSF), availability, busy period of the server due to hardware and software failures, expected number of replacements due to hardware and software failure, expected number of visits by the server are derived by adopting semi-Markov process and regenerative point technique. The numerical results for a particular case are obtained to depict the graphical behavior of some measures of system effectiveness.