Overview

You can add standby instances to an OceanBase Cloud instance to form a one-primary-and-multiple-standby cluster network. Data is synchronized between the primary and standby instances to enhance the high availability of the database. Currently, you can deploy primary and standby instances in the same cloud or across clouds.

Principles

OceanBase Cloud supports various primary-standby deployment architectures, including primary-standby instances in the same cloud and across clouds. Data is synchronized between the primary and standby instances through asynchronous log replication. This process does not affect the stability and performance of the primary instance.

Primary and standby instances in the same cloud

Primary-standby instances in the same cloud are deployed on the same cloud service provider. For more information, see Create a standby instance in the same cloud.

Standby instances in the same cloud have the following advantages:

• Simplified management: All resources are located within the same cloud, so configuration, monitoring, and maintenance are easier, and you can use the built-in tools and services of the cloud vendor for unified management.

• Lower network latency: The network latency between the primary and standby instances deployed within the same cloud is lower than that between primary and standby instances across clouds vendors. This results in higher data synchronization efficiency, which is particularly important for applications that require high real-time performance.

• Better integration and compatibility: The database services of the same cloud have better integration and consistency in terms of security policies, identity authentication, and APIs. This simplifies system development and O&M.

• Clear cost: The cost structure is clear, and there are no additional costs for cross-cloud data transmission. This allows enterprises to easily predict and control cloud service costs.

Primary-standby instances across clouds

• Create a database instance with one primary instance and multiple standby instances across clouds

  Deploy a primary instance and one standby instance in Cloud A, and another standby instance in Cloud B. Alternatively, deploy a primary instance in Cloud A and two standby instances in Cloud B. This forms a one-primary-and-multiple-standby relationship across clouds.

  • The primary instance provides read and write services, while the standby instances synchronize data in real-time through Redo logs to maintain data consistency.

  • Log synchronization chain: The primary instance transmits transaction logs to each standby instance in real-time via the Log Transport Service. The standby instances apply these logs to the MemStore in memory through the Log Replay Service, achieving data synchronization between primary and standby instances.

  • Global address: Applications access the database through a global address, which serves as a unified entry point and automatically routes traffic to the current primary instance. When a primary-standby switch occurs, the global address automatically points to the new primary instance, allowing applications to switch seamlessly without modifying connection configurations.

  • Application connection method: Multiple business instances connect to their respective OceanBase instances in each cloud through a VPC network and access the database through the global address, ensuring automatic traffic routing during switches.

• Create a database instance with one primary instance and one standby instance across clouds

  This architecture consists of a primary cloud (Cloud A) and a standby cloud (Cloud B), providing high availability and disaster recovery capabilities. Each cloud platform has two regions, Region A and Region B, with independent database instances and OSS object storage services deployed.

  • Cloud A efficiently distributes data through internal write routing.

  • Cross-cloud synchronization ensures data consistency between primary and standby instances by synchronizing data over the public internet.

  • You can view the synchronized data in the standby instance on Cloud B.

  

Use cases

The primary and standby instance architecture applies to the following scenarios:

• Intra-city disaster recovery

  In some regions supported by OceanBase Cloud, only two zones are provided, which means a single OceanBase instance with three replicas cannot ensure disaster recovery at the zone level. In such cases, you can deploy primary and standby instances across two zones to achieve high availability. If a failure occurs in one zone, you can manually switch operations to the standby instance.

• Cross-region disaster recovery

  For businesses deployed across multiple regions, you can set up primary and standby instances in different regions to achieve cross-region high availability. If a failure occurs in one region, you can manually switch operations to the standby instance.

Differences between primary and standby instances