In this work, a general closed-form expression is presented for the lifetime reliability of load-sharing -out-of-:G hybrid redundant systems. In such systems, components are initially configured as active units. Depending on whether it is performing tasks, an active component can be in either a processing, or a wait state. Each state corresponds to an arbitrary failure distribution. The remaining ( ) are spares to provide fault tolerance. Each time an active component fails, a spare one

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... into active mode, until there are no more spares in the system. Then, the system works in a gracefully degrading manner such that less than components share the workload, until the number of good components is less than . The task allocation, and service are modeled as queueing systems, wherein the utilization ratio essentially affects the aging effect of components. We integrate the various failure distributions for components in different operational states into an analytical model according to the statistical properties of the task allocation mechanisms, and the components' processing capacity, and analyse the lifetime reliability of the entire system. Finally, three special cases, and a series of numerical experiments are discussed in detail to show the practical applicability of the proposed approach. Index Terms-Arbitrary distribution, hybrid -out-of-:G system, load-sharing, queueing model. ACRONYM CMOS complementary metal-oxide semiconductor FIFO first-in-first-out IC integrated circuit MTTF mean time to failure Manuscript .hk). Q. Xu is with the CUhk REliable computing laboratory (