System Robustness Hierarchy

CORE DEFINITION

The robustness hierarchy is the practice of grading components of a system by the consequence of their failure and then setting a matching requirement for resistance to disturbance: critical components receive redundancy or fault tolerance, while peripheral ones accept higher vulnerability. The core proposition is that robustness resources are finite, so distributing them evenly wastes capacity on parts whose failure the system can absorb while leaving critical parts under-protected. The key qualification is that the grading must account for dependencies between components, since a peripheral part that many others rely on carries the consequence of a critical one.