High‑Availability Strategies for Stateful Backend Services: Cold Backup, Dual‑Machine Active/Standby, Same‑City and Cross‑City Active‑Active, and Multi‑Active Architectures
The article explains various high‑availability solutions for stateful backend services, comparing cold backup, dual‑machine active/standby, same‑city active‑active, cross‑city active‑active, and cross‑city multi‑active approaches, and discusses their trade‑offs, implementation details, and real‑world examples from large internet companies.