Deploy app servers in regions close to users; use global DNS or CDN to route traffic. Replicate or partition data according to consistency needs. Multi-region adds complexity; start with primary and one failover region.
Why multi-region
- Latency: Users get lower latency when app servers are in their region. Use geo DNS or CDN to direct traffic to the nearest region.
- Resilience: If one region fails, traffic can fail over to another. Reduces single-point-of-failure at the DC or region level.
- Compliance: Data residency may require running (or storing data) in specific regions (e.g. EU for GDPR).
Traffic and DNS
- Global DNS: Return different A/AAAA records by geography (geo DNS) so clients resolve to the nearest region. Lower TTL if you may change records (e.g. failover).
- CDN: For static or cacheable content, CDN edge locations give low latency without running app servers everywhere. Origin can be single- or multi-region.
- Load balancer: Global load balancer (e.g. provider or cloud) can route to regional backends and do health-based failover.
Data
- Replication: Async or sync replicate DB/cache to another region for read scaling or failover. Consistency and conflict handling get complex.
- Partitioning: Shard or partition data by region so each region owns a subset. Simpler consistency but cross-region access has latency.
- Start simple: Primary in one region, read replica or standby in another for failover. Add more regions as needed.
Summary
Multi-region improves latency and resilience. Use global DNS or LB to route traffic; replicate or partition data per consistency needs. Start with primary + one failover region.
