On the value of redundancy subject to common-cause failures: Toward the resolution of an on-going debate
On the value of redundancy subject to common-cause failures: Toward the resolution of an on-going debate
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DOI：
10.1016/j.ress.2009.06.007
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发表时间：
2009-12
期刊：
影响因子：
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通讯作者：
V. M. Hoepfer;J. Saleh;Karen B. Marais
中科院分区：
文献类型：
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作者：
V. M. Hoepfer;J. Saleh;Karen B. Marais
共因故障是系统可靠性和风险分析中最关键和最具挑战性的问题之一。学术界对CCF建模的兴趣，以及更广泛地对相关故障建模的兴趣，多年来在出版物的数量以及所使用的分析工具的复杂性方面稳步增长。在过去的几年里，一些有影响力的文章对冗余的相关性提出了质疑，认为“冗余适得其反”通过共因故障，后者主导了不可靠性，从而挫败了冗余的目的。在这项工作中，我们对这些出版物的一些结果提出异议。取而代之的是，我们提供了一个微妙的角度来看（或有）价值的冗余受到共同原因的故障。首先，我们审查的增量可靠性和MTTF冗余共因故障提供。其次，我们引入的概念，并开发分析的“冗余相关性边界”：我们提出这个冗余相关性边界作为一个设计辅助工具，提供了一个答案以下问题：什么水平的冗余度是相关的或有利的不同流行的常见原因的故障？我们调查的条件下，不同程度的冗余提供了一个增量MTTF超过单一组件在面对常见原因的故障。认识到冗余是有成本的，我们还进行了成本效益分析冗余共因故障，并演示了如何修改冗余相关边界的分析。我们展示了冗余的价值是如何取决于共因故障的发生率，考虑的冗余水平，和一元成本效益比。最后，我们认为，一般不合格的批评冗余是误导，努力更好地花在例如理解和减轻潜在的共同原因故障的来源，而不是嘲笑冗余的概念，在系统设计。
Common-cause failures (CCF) are one of the more critical and challenging issues for system reliability and risk analyses. Academic interest in modeling CCF, and more broadly in modeling dependent failures, has steadily grown over the years in the number of publications as well as in the sophistication of the analytical tools used. In the past few years, several influential articles have shed doubts on the relevance of redundancy arguing that “redundancy backfires” through common-cause failures, and that the latter dominate unreliability, thus defeating the purpose of redundancy. In this work, we take issue with some of the results of these publications. In their stead, we provide a nuanced perspective on the (contingent) value of redundancy subject to common-cause failures. First, we review the incremental reliability and MTTF provided by redundancy subject to common-cause failures. Second, we introduce the concept and develop the analytics of the “redundancy–relevance boundary”: we propose this redundancy–relevance boundary as a design-aid tool that provides an answer to the following question: what level of redundancy is relevant or advantageous given a varying prevalence of common-cause failures? We investigate the conditions under which different levels of redundancy provide an incremental MTTF over that of the single component in the face of common-cause failures. Recognizing that redundancy comes at a cost, we also conduct a cost–benefit analysis of redundancy subject to common-cause failures, and demonstrate how this analysis modifies the redundancy–relevance boundary. We show how the value of redundancy is contingent on the prevalence of common-cause failures, the redundancy level considered, and the monadic cost–benefit ratio. Finally we argue that general unqualified criticism of redundancy is misguided, and efforts are better spent for example on understanding and mitigating the potential sources of common-cause failures rather than deriding the concept of redundancy in system design.