Affordable Fault Tolerance Through Adaptation

Fault-tolerant programs are typically not only difficult to implement but also incur extra costs in terms of performance or resource consumption. Failures are typically relatively rare but the fault-tolerance overhead must be paid regardless if any failures occur during the program execution. This paper presents an approach that reduces the cost of fault-tolerance, namely, adaptations to a change in failure model. In particular, a program that assumes no failures (or only benign failures) is combined with a component that is responsible for detecting if failures occur and then switching to a fault-tolerant algorithm. Provided that the detection and adaptation mechanisms are not too expensive, this approach results in a program with smaller fault-tolerance overhead and thus a better performance than a traditional fault-tolerant program. Thus, the high cost of fault-tolerance is only paid when failures actually occur.