Evaluation and comparison of fault-tolerant software techniques

Four implementations of fault-tolerant software techniques are evaluated with respect to hardware and design faults. Project participants were divided into four groups, each of which developed fault-tolerant software based on a common specification. Each group applied one of the following techniques: N-version programming, recovery block, concurrent error-detection, and algorithm-based fault tolerance. Independent testing and modeling groups analyzed the software. The testing group subjected it to simulated design and hardware faults. The data were then mapped into a discrete-time Markov model developed by the modeling group. The effectiveness of each technique with respect to availability, correctness, and time to failure given an error, as shown by the model, is contrasted with measured data. The model is analyzed with respect to additional figures of merit identified during the modeling process, and the techniques are ranked using an application taxonomy