Combinatorial Reliability Analysis of Warm-Standby Systems with Imperfect Fault Coverage

Warm Standby redundancies are used for improving the reliability in various applications requiring a fast system restoration and minimal energy consumption. Warm-standby redundancies introduce sequential dependent failure behavior between the online unit and the standby units; in particular, failure rates of the standby units change after replacing the on-line faulty unit. Moreover, when the system components are subject to uncovered/undetected fault, the entire system fails despite the presence of remaining redundancies. This paper models the reliability of 1-out-n warm-standby sparing systems subject to imperfect fault coverage based on Sequential Multistate Decision Diagrams (SMDD). The proposed method can overcome some limitations of existing works on warm-standby systems with imperfect fault coverage, such as assuming exponential time-to-failure distribution for all the system components or considering only one warm standby unit. An illustrative example is given to show advantages and applications of the proposed SMDD-based method.