Maintenance plays an important role in system reliability enhancement which is an essential requirement for computer systems in service for critical applications. This paper presents a failure number m based maintenance policy for k-out-of-n:G loadsharing computer systems with a goal of maximizing the long-run expected system reward per unit time. Compared to previous study, we take load-sharing into account and employ tampered failure rate (TFR) model to describe failure rate change caused by

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... oadsharing. With some typical numeral examples, we analyzed expected system reward rate under different load stress level and achieved corresponding optimal value of decision variable m. The result shows that component failure has much more impact on heavily loaded system than lightly one, and optimization of maintenance action depends greatly on the load level.