Availability

Resource partitioning, shuffle sharding, cellular architecture

CAP theorem and PACELC extension; Kleppmann's critique ("best avoided"); timeliness vs integrity distinction

definition, prerequisites, experiment design, injection types (Chaos Monkey/Latency Monkey/FIT), targeting strategy, automation and moderation, disaster simulations; theoretical foundations (drift into failure, regulator paradox, antifragility); complex systems foundations (accidental vs essential complexity, emergent failures, composability of safety); Netflix origin story; Chaos Maturity Model

data plane (on critical path, availability), control plane (off-path, consistency); static stability; scale imbalance solutions (file store buffer, push deltas, hybrid); control theory feedback loop

Nines table with money attached; conversion via downtime cost; investment cost per nine; where each nine is earned; antipatterns (tyranny of the nines, MTBF without MTTR, redundancy without isolation); architectural choices that make availability cheap or expensive

Hierarchical resolution process; TTL trade-offs; DNS as eventually consistent KV store; DNS as SPOF; static stability principle

error budget = 1 − SLO target; resolves dev/ops conflict by aligning incentives; budget exhaustion triggers release freeze; burn rate alerting; 100% is wrong target argument

DNS LB, L4 (transport), L7 (application), service discovery, health checks, power of two choices, sidecar as client-side LB; stateless services as prerequisite for scale-out

*Site Reliability Engineering* — Beyer, Jones, Petoff, Murphy