This paper considers the M/M/N repairable queuing system. The customers' arrival
is a Poisson process. The servers are subject to breakdown according to Poisson processes with
different rates in idle time and busy time, respectively. The breakdown servers are repaired by repairmen,
and the repair time is an exponential distribution. Using probability generating function
and transform method, we obtain the steady-state probabilities of the system states, the steady-state
availability of the servers, and the mean queueing length of the model
