A model is presented that can be used to study the influence of machin
e breakdown and limited repair capacity on the performance of a system
that has to provide service continuously. We consider a system consis
ting of N stations, each serving its own stream of customers. The serv
ers of the stations are subject to breakdown. Broken servers are repai
red by a joint repair facility consisting of K parallel repairmen. Whe
never K < N, this repair facility is causing interference between the
N stations. We present both an exact (matrix-geometric) solution and a
simple approximation (employing stochastic decompositions) of the dis
tribution of the queue length at a particular station. With this model
various design issues can be investigated such as the number of repai
rmen that is needed to maintain a pool of machines, or the number of m
achines that can be assigned to a certain crew of repairmen. Several n
umerical examples illustrate the approach.