Evaluation of fault-tolerant systems with nonhomogeneous workloads

A methodology is presented for evaluating fault-tolerant systems when workloads and fault arrivals are not time-homogeneous. Of particular interests are systems whose environments vary considerably between different utilization phases of random duration. In such cases, evaluations of overall system performability must account for the corresponding differences in workload effects, especially with regard to fault recovery. The proposed methodology uses analytic techniques based on Markov processes and stochastic activity networks. Examples of evaluation studies, using this approach, are presented. These include evaluation of a system wherein self-exercising is varied between phases of passive and active use.<>