multiple spares and switching failure

This paper deals with a machine-repair problem involving multiple warm standby and two heterogeneous repairmen where repairmen render essential repair and optional repair. The first repairman is present all the time to repair the failed components whereas the second repairman takes a vacation of random extent whenever the number of failed components is fewer than N. The second repairman returns back and renders repair jobs when the number of failed units reaches N. Essential repair is provided to each failed unit, whereas few of them demand the second optional repair. The concept of standby switching failure is incorporated with degradation and common cause failure. The steady-state equations governing the system are developed and a matrix technique to obtain the steady state probabilities of the system is employed. We provide explicit expressions to obtain performance measures of the system. For validation purpose, sensitivity analysis is carried out by taking numerical illustrations.