Name all 5 diagram types and state the single question each is designed to answer. For each diagram, name the failure mode it is most likely to surface.
A senior engineer says: “I can put the whole system in one diagram — separate diagrams are just extra work.” What is wrong with this argument? Give a concrete example where a single diagram would hide a failure mode that one of the five focused diagrams would surface.
You are drawing D5 (Distributed Coordination) for a system that uses a managed database with automatic leader failover. What does the diagram show? What question must it answer about the failover window that D1 cannot?
D3 (Event-Driven) and D4 (Data Pipeline) both involve async data movement. What is the structural difference between them? Give an example of a system where you need to draw both.
A post-mortem reveals that a cascade failure was caused by a slow external API call blocking the application thread pool. Which of the five diagrams, if drawn during design, would have made this risk visible? What specifically on the diagram would have been the warning signal?
Concept: F7 — The 5 Architecture Diagrams
Thread: T10 (Encoding) ← Representation (Book 1, Ch 10) → Communication in architecture review (Book 6, Ch 7)
Core Idea: Five diagram types — Request Flow, Data Storage, Event-Driven, Data Pipeline, Distributed Coordination — each answer one specific question about a system that the others cannot. Drawing all five reveals the complete failure surface. Each diagram must show the failure path, not just the happy path.
Tradeoff: Simplicity vs Flexibility (F4 #3) — one comprehensive diagram is simpler to produce but obscures the different concerns; five focused diagrams are more work but reveal more
Failure Mode: FM11 (Observability Blindness) — the diagram you do not draw is the diagram that hides the failure mode that becomes your next incident
Signal: Onboarding to a new system; designing a new system; preparing for an architecture review; debugging a production incident
Maps to: Reference Book Ch 10 (F6 Archetypes — each archetype has a characteristic diagram emphasis); Book 4 (every system design chapter uses all 5 diagrams); Book 6 Ch 5 (architecture review process)