Redundancy and Reliability Tradeoffs for Safety/Mission Critical Systems

摘要

We investigate and analyze the concept of “asymmetry” and its application to the design of architecturesthat integrate multiple safety/mission critical functions or subsystems. The concept of asymmetry is basedon considering different design alternatives that would result by “trading off” reliability with varying levelsof physical redundancy of the components constituting the functions or subsystems. Under a set ofassumptions, we show that the overall system reliability and availability in an asymmetric architecture(varying Mean Time To Failure or MTTF of the constituent components) can be kept constant withoutincreasing the levels of physical redundancy for the components employed at the subsystem level.However, such behavior will be achieved only by judiciously choosing the MTTF for components withlimited level of redundancy.