20 — Idempotency

Site Reliability Engineering: From Foundations to Internet-Scale Systems

The complete 184-chapter, 15-part Site Reliability Engineering curriculum — from Linux internals and distributed-systems theory through reliability engineering, observability, incident response, platform engineering, and Staff/Principal-level MAANG interview preparation, ordered the way SRE expertise actually develops rather than as a topic index.

1 — Reliability Principles

The handful of first-principles ideas — redundancy, graceful degradation, known failure modes — that every other chapter in this Part is a specific application of.

10 — Failure Domains

Drawing the boundary around 'what breaks together' — AZ, region, tenant, deploy group — so a single fault has a bounded, known blast radius instead of an open-ended one.

11 — Redundancy Patterns

Active-active, active-passive, and N+1 redundancy, and the trade-off each makes between failover speed, cost, and the complexity of keeping replicas actually consistent.

12 — Graceful Degradation

Designing a system to shed non-critical functionality under stress instead of failing completely — and deciding in advance what's non-critical.