DEPENDABILITY EVALUATION OF HIERARCHICAL SYSTEMS

Hierarchical design represents a natural solution for managing the gro wing complexity of computing systems. This leads to systems that are h ierarchically structured from a logical or physical viewpoint. Because of the inherent complexity of such systems, the incorporation of faul t-tolerance features is highly recommended, to achieve the required de pendability level. Hence, it is important to develop evaluation tools that allow to analyse the effectiveness of different fault-tolerance m echanisms. We present a systematic procedure for the construction and evaluation of Markov models for transient dependability analysis, whic h fully exploits the hierarchical structure of the system under evalua tion. A thorough time/space complexity analysis of the proposed proced ure shows that it allows a considerable time and space saving with res pect to a ''naive'' approach to the same problem.