Stepwise Refinement of Complex Dependability Models Using LARES+

This article shows how the method LARES+ (Language for Reconfigurable Systems) is used to model a realistic fault-tolerant computer system comprising 60 components by step-wise refinement. The system under consideration has a highly irregular redundancy structure. Components are not assumed to be independent. In contrast, it is assumed that dormant components fail with a reduced failure rate, and that failure detection and reconfiguration is imperfect.