OceanBase Database introduces the arbitration service since this version. The arbitration service not only prevents the increase of response time (RT) due to the failure of replicas in the same city in the deployment mode of three IDCs across two regions, but also reduces the cross-city bandwidth overhead and minimizes the costs of the third IDC.
The arbitration service maintains the arbitration members of tenant log streams. An arbitration member has the following characteristics:
An arbitration member votes in leader election, Paxos Prepare, and member group change, but does not participate in Paxos Accept.
An arbitration member does not have a MemTable or SSTable. Therefore, it does not store logs and consumes minimal bandwidth, memory, disk, and CPU resources.
An arbitration member cannot be elected as a leader to provide services.
If half of the full-featured replicas in a cluster fail, which means the logs on the majority of replicas cannot be synchronized, the arbitration service enables the cluster to automatically downgrade to restore the database services, with a recovery point objective (RPO) of 0. After the failed replicas are recovered, the cluster automatically upgrades and restores the original replica list.
More information
For more information about the arbitration service, see the following topics: