Multiple Backup Resource Allocation with Workload-Dependent Failure Probability

This paper proposes a multiple backup resource allocation model with a workload-dependent failure probability to minimize the maximum expected unavailable time (MEUT) under a protection priority policy. The workload-dependent failure probability is a monotonically increasing function which reveals the relationship between computing 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 workloads before failures occur to reduce resource utilization with the cost of long recover time. The hot backup strategy is a protection strategy, in which the backup resources execute at the same time with functions to recover promptly with the cost of high workload. For protection of each function with multiple backup resources, it is required to adopt a suitable priority policy to determine the expected unavailable time. We analyze the superiority of the protection priority policy for multiple backup resources in the proposed model and provide the theorems that clarify the influence of policies on MEUT. The numerical results show that the proposed model reduces MEUT compared with the single backup model in which each function is protected by only one server without protection priority of servers. The priority policy adopted in the proposed model specifying that the server which adopts the hot backup strategy has higher priority than that with the cold backup strategy for multiple backup resources suppresses MEUT compared with other priority policies.