Fault-tolerant system dependability-explicit modeling of hardwareand software component-interactions

摘要

This paper presents a framework for modeling the dependability ofnhardware and software fault-tolerant systems, taking into accountnexplicitly the dependence among the components. These dependencies cannresult from: (a) functional or structural interactions between thencomponents or (b) interactions due to global system reconfiguration andnmaintenance strategies. Modeling is based on GSPN (generalizednstochastic Petri net). The modeling approach is modular: the behavior ofneach component and each interaction is represented by its own GSPN,nwhile the system model is obtained by composition of these GSPN.nComposition rules are defined and formalized through clearnidentification of the interfaces between the component and interactionnnets. In addition to modularity, the formalism brings flexibility andnre-usability, thereby allowing easy sensitivity analysis with respect tonthe assumptions that could be made about the behavior of the componentsnand the resulting interactions. This approach has been successfullynapplied to select new architectures for the French Air Traffic Controlnsystem, based among other things, on availability evaluation. This papernillustrates it on a simple representative example, including all thentypes of the identified dependencies: the duplex system. Modeling ofnthis system showed the strong dependence between components