Active-active runs full capacity in multiple regions simultaneously.
Architecture:
- All regions serve production traffic
- Data replicated between regions
- Global load balancer routes by geography
Benefits:
- No failover delay (all regions always active)
- Lower latency (users hit nearest region)
- Full capacity always available
Challenges:
- Data consistency across regions
- Conflict resolution for writes
- x+ infrastructure cost
Use when downtime is unacceptable and you can handle eventual consistency.