Intrinsic Redundancy for Reliability and Beyond

Software redundancy is an essential mechanism in engineering. Different forms of redundant design are the core technology of well-established reliability and fault-tolerant mechanisms in traditional engineering as well as in software engineering. In this chapter, we discuss intrinsic software redundancy, a type of redundancy that is not added explicitly at design time to improve runtime reliability but is natively present in modern software system due to independent design and development decisions. We introduce the concept of intrinsic redundancy, discuss its diffusion and the reasons for its presence in modern software systems, indicate how it can be automatically identified, and present some current and future applications of such form of redundancy to produce more reliable software systems at affordable costs.