Design of multi-level fault tolerant systems

The literature on reliable systems is composed by a very broad range of specific problems and solutions. Very few designs of reliable systems are reported, in which an integrated methodology is taken into account as one of the most important design goals. This fact makes, in general, difficult to provide a good readability and possibility of evaluation of the proposed solutions for enhancing the reliability of these systems. The aim of this paper is to provide a structured methodology and several implementative suggestions for the design of failure tolerant systems. The overall approach does not explicitly differentiate between hard or soft objects and allows the treatment of failure tolerance from the first design phases.