• RELIABILITY AND PROFIT ANALYSIS OF A COMPUTER SYSTEM WITH SOFTWARE REPLACEMENT AND ARRIVAL TIME OF THE SERVER AT HARDWARE FAILURE

Abstract

This paper presents a reliability model for a computer system of two identical units- one is operative and other is kept as spare in cold standby. In each unit, h/w and s/w components fail independently from the normal mode. There is a single server who takes some time to arrive at the system for repair of the unit at its h/w failure while he comes immediately to make replacement of the s/w by new one in the unit with some replacement time when s/w fails to meet out the requirements. The distribution of failure time of the unit is taken as negative exponential with different failure rates of h/w and s/w components, whereas repair time of h/w, replacement rate of the s/w and arrival time of the server are arbitrarily distributed with different probability density functions (pdf). To carry out reliability and profit analysis, the expressions for some important measures of the system effectiveness are derived in steady state using semi-Markov process and regenerative point technique. The graphical study of the results has been made for a particular case. The MTSF and profit of the present model have also been compared with that of the model investigated by Malik and Sureria [2012].