Practical View of Redundancy Management Application and Theory

A perspective is developed on how redundancy management techniques for e ight-critical systems have matured sincetheearliestapplicationsin the1960s,driven largelybytheintroduction ofmorepowerfulcomputerresources. As this evolution occurred, the basic issues involving system architecture tradeoffs changed very little, although the hardware mechanizations of the earlier analog systems have been replaced largely with the software of the newerdigital systems.Thesebasicissuesarereviewed and howthey tend to beresolvedinpractical mechanizations is shown. The large body of literature on analytic redundancy theory developed since the 1970s is discussed in the context of its applicability to practical systems. It is shown that analytic redundancy has an important role in real-world systems but that it is not a replacement for physical redundancy, and its proper implementation requires that it be embedded within the physical redundancy structure of the system.