Optimal Time and Random Inspection Policies for Computer Systems
Optimal Time and Random Inspection Policies for Computer Systems
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发表时间：
2014
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通讯作者：
Xufeng Zhao;Mingchih Chen;T. Nakagawa
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作者：
Xufeng Zhao;Mingchih Chen;T. Nakagawa
计算机系统中的故障有时会间歇性地发生。本文对计算机系统采用不完全检验的标准检验策略：系统在周期性时刻被检验，其故障以一定的概率在下一次检验时被检测到。得到了直到失效检测的期望费用，并在失效时间为指数函数时，导出了使其最小的最优检测时间。接着，当系统执行计算机处理时，在随机处理时间对其进行检查，并且在下一个检查时间以一定概率检测到其故障。得到了故障检测前的期望成本，并在随机处理时间为指数函数时，导出了使其最小的最优检测时间。本文比较了两种检验策略的最优时间，证明了当随机检验费用是周期检验费用的一半时，两种检验策略的期望费用几乎相等。最后，我们考虑了随机检查策略，其中系统在第N个随机时间间隔进行检查，并导出了使总期望成本最小的最优数N。
Faults in computer systems sometimes occur intermittently. This paper applies a standard inspection policy with imperfect inspection to a computer system: The system is checked at periodic times and its failure is detected at the next checking time with a certain probability. The expected cost until failure detection is obtained, an d when the failure time is exponential, an optimal inspection time to minimize it is derived. Next, when the system executes computer processes, it is checked at random processing times and its failure is detected at the next checking time with a certain probability. The exp ected cost until failure detection is obtained, and when random processing times are exponential, an optimal inspection time to minimize it is derived. This paper compares optimal times for two inspection policies and shows that if the random inspection cost is the half of the periodic one, then two expected costs are almost the same. Finally, we consider the random inspection policy in which the system is checked at the Nth interval of random times and derive an optimal number Nwhich minimizes the total expected cost.