The provision of additional components in a system, over and above the minimum set of components needed to perform the functions of the system, for purposes of reliability or robustness. For example, with triple modular redundancy three components are deployed in parallel, all performing the same function. Their outputs are compared, and when one component produces a different result from the other two, this item is assumed to be faulty and is ignored. Redundancy covers not only the incorporation of duplicate or triplicate hardware for backup in case of failure, but also the inclusion of excess symbols in messages sent through communication systems in order to combat the effects of noise (see error-correcting code, error-detecting code).
Subjects: Computing — Astronomy and Astrophysics.