Paxos Quorum Design for Multi-Region

Multi-region OceanBase deployments must balance RPO/RTO targets against write latency. Paxos requires a majority of replicas to acknowledge each log append.

Three-region active

Place 2 replicas in primary region, 1 in each secondary. Quorum = 2, so the primary region can survive alone. Cross-region writes wait for at least one remote ACK unless using degraded quorum policies (not recommended for financial workloads).

Two-region with arbitration

Use a lightweight arbitration or witness replica in a third site (even object storage based) to break ties. Without it, losing either region loses quorum.

Failover testing

Quarterly, run controlled leader transfer:

ALTER SYSTEM SWITCH REPLICA LEADER
  LOGSTREAM 1001 SERVER '10.0.1.12:2882';

Measure client error rate and OBProxy redirect time. Document expected 3–8s blip for unprepared clients.