Profit Analysis of a Computer System with H/W Repair and S/W Replacement

The main intension of this paper is to make profit analysis of a computer system of two identical units in which one unit is operative and other is kept as cold standby. In each unit, h/w and s/w components fail independently from the normal mode. A single server visits the system immediately whenever needed to carry out repair and replacement of the components. If there is a h/w failure in the unit, then that unit goes immediately under repair. However, only replacement of the s/w in the unit is made by new one whenever s/w fails to meet out the requirements. The failure time of the unit is exponentially distributed while the distributions of repair rate of h/w and replacement rate of the s/w are taken as arbitrary with different probability density functions (pdf). The expressions for several reliability characteristics are derived by making use of semi-Markov process and regenerative point technique. Graphs are drawn for a particular case to highlight the behaviour of some measures of system effectiveness. The results of the present model have also been compared with the results obtained for the model proposed by Malik and Anand [4].