Optimal Primary and Backup Resource Allocation with Workload-Dependent Failure Probability

This paper proposes an optimization model to derive a primary and backup resource allocation considering a workload-dependent failure probability to minimize the maximum expected unavailable time (MEUT). The workload-dependent failure probability is a monotonically increasing function which reveals the relationship between workload and failure probability. The proposed model adopts hot backup and cold backup strategies to provide protection. The cold backup strategy is a protection strategy, in which the requested loads of backup resources are not processed as active workload before failures occur to reduce resource utilization with the cost of longer recover time. The hot backup strategy is a protection strategy, in which the backup resources execute at the same time with primary resources to recover promptly with the cost of high workload. We formulate the optimization problem as a mixed integer linear programming (MILP) problem with extensive mathematical operations. The numerical results show that the proposed model suppresses MEUT compared with the conventional model which does not consider the workload-dependent failure probability by combining the benefits of hot backup and cold backup strategies with the workload-dependent failure probability.