Comparative Cost‐Benefit Analysis of Four Retrial Systems With Warm Standby Components and Two Modes of Failure

ABSTRACT This paper studies the availability of four retrial configurations for a machine repair problem with warm standby units where the units have two failure modes. The two failure modes for each unit have the same probability of being repaired. The unit failure times and server repair times are assumed to be independent and exponentially distributed. For each retrial configuration, the state‐transition rate diagram and the differential‐difference equations are exploited to derive steady‐state availability. We provide a comparative analysis and determine the best retrial system based on a suitable performance selected. The four retrial configurations are ranked in terms of their steady‐state availability and cost/benefit ratios, where the benefit is steady‐state availability. We compare the cost/benefit ratios of the four retrial configurations given the distribution parameters and acquisition, operation, and maintenance costs.