The authors obtain an optimal operation policy for a general n-server (channel, machine) stand-by system involving preventive maintenance and operating in real time. They show that such a policy is achieved by successive total use of each server capacity, and does not depend on the arrival pattern of processed data and task duration. The authors show also that this policy is optimal for any finite, inital period of time, and not only in the sense of long-run availability. The analysis is performed in two stages: a worst-case analysis is performed, and then, a general case is treated. Such a consecutive approach also seems to be useful in the analysis of more complicated systems. Rigorous mathematical proofs are provided. Actual and possible applications of results to military and production control systems are discussed.
