Stage 1 · Lesson 4 of 7
Failure modes and blast radius
Every design should say how it fails, not only how it works. For each dependency, ask what happens when it is slow, down or sending back bad data. Then ask how far the damage spreads.
That spread is called the . Systems shared by teams have their own failure modes. One team's client retries too eagerly and floods another team's service (a ).
A shared cache fails and takes everything down together. A schema change, a change to the shape of the data, breaks a consumer nobody knew about. A few standard tools limit the blast radius: timeouts, that stop calling a failing service, bulkheads that keep parts isolated, and , where a feature works less well instead of failing outright. SLOs, next, turn this into numbers teams can agree on.
Common trapreviewing only the happy path in a , and discovering the failure modes in the first incident.
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Resources for this stage
Start with· follow one of these
- CoursePaidSystem Design Patterns: From Fundamentals to Real Systems
Design Gurus · Intermediate · Subscription
The distributed patterns behind most designs, to judge proposals from other teams
- GuideFreeMartin Fowler's Website
Martin Fowler · Intermediate
Free, clear writing on architecture styles, microservices and evolving designs