System Level Dependability Analysis

The focus of this work is on the dependability analysis of safety or mission-critical systems; in particular, we concentrate on the control subsystem, which is made up of several components. We assume that the components, which may be designed with the support of hardware—software codesign tools, are characterized by dependability (e.g. failure rate) parameters, which may derive from simulators of the components while they are under development, or as a result of testing (possibly combined with fault injection techniques). By using combinatorial and state-space-based techniques it is possible to derive the reliability of the whole system as a function of the system configuration and of the component parameters values, and to identify the criticality of a given component or subset of components. The analysis is performed by applying Fault Tree Analysis (FTA) techniques enhanced with recently introduced features that allow one to remove the components’ independence assumptions imposed by classical FTA, and to include the possibility of component as well as subsystem repair.