Elements in a system can be protected by incorporating a weak link. The weak link protects the rest of the system by failing first. Thus, the weakest link is one of the most important elements in the system.
To design a protective, weak link:
- identify a failure condition
- identify the weakest link in the system for that failure condition
- further weaken the weakest link and strengthen the other links as necessary
- ensure that the weakest link will only fail under the appropriate, predefined failure conditions
Universal Principles of Design; Lidwell, Holden, Butler
The weakest chain link analogy only works in linear systems. Systems are often non-linear and much more difficult to manage. Think “food chain” vs “food web” in an ecology.
Interruptions in a complicated system may have unintended consequences or not be slowed by a “weak link” at all.
It is also often the case that a system needs to be designed to withstand errors or handle errors in a helpful manner while continuing operations
The “blue screen of death” is frustrating because it is a total halt of operations, without helpful feedback about the error. Most users would prefer for the system to withstand and contain the error with feedback.