Analysis of workload influence on dependability

The authors consider a general, analytic approach to the study of workload effects on computer system dependability, where the faults considered are transient and the dependability measure in question is the time to failure, T/sub f/. Under these conditions, workload plays two roles with opposing effects: it can help detect/correct a correctable fault, or it can cause the system to fail by activating an uncorrectable fault. As a consequence, the overall influence of workload on T/sub f/ is difficult to evaluate intuitively. To examine this in more formal terms, the authors establish a Markov renewal process model that represents the interaction among workload and fault accumulation ins systems for which fault tolerance can be characterized by fault margins. Using this model, they consider some specific examples and show how the probabilistic nature of T/sub f/ can be formulated directly in terms of parameters regarding workload, fault arrivals, and fault margins.<>