Queueing Analysis of Fault-Tolerant Computer Systems

In this paper we consider the queueing analysis of a fault-tolerant computer system. The failure/repair behavior of the server is modeled by an irreducible continuous-time Markov chain. Jobs arrive in a Poisson fashion to the system and are serviced according to FCFS discipline. A failure may cause the loss of the work already done on the job in service, if any; in this case the interrupted job is repeated as soon as the server is ready to deliver service. In addition to the delays due to failures and repairs, jobs suffer delays due to queueing. We present an exact queueing analysig of the system and study the steady-state behavior of the number of jobs in the system. As a numerical example, we consider a system with two processors subject to failures and repairs.