Physical Standby Database is an important part of the high availability solution of OceanBase Database. When the primary database becomes unavailable as planned or due to an exception such as a failure of the majority of replicas, the standby database takes over the services and perform a switchover to minimize the service interruption time. Two switchover modes are supported: lossless switchover with a recovery point objective (RPO) of 0 and lossy switchover with an RPO greater than 0.
In OceanBase Database of a version earlier than V4.1.0, the Physical Standby Database solution is provided in the form of primary/standby clusters. Two cluster roles exist: primary cluster and standby cluster. All user tenants in the primary cluster are primary tenants, and all user tenants in a standby cluster are standby tenants. The standby cluster automatically synchronizes the tenant change operations performed in the primary cluster.
Since V4.1.0, the Physical Standby Database solution is provided in the form of primary/standby tenants. Clusters are no longer assigned the primary or standby role and are only containers of tenants. Two user tenant roles exist: primary tenant and standby tenant. The primary tenant is a business tenant that supports complete database capabilities, including queries, data manipulation language (DML) operations, and data definition language (DDL) operations. A standby tenant provides only disaster recovery and read-only services. The tenant-level Physical Standby Database high availability solution comprises one primary tenant and multiple standby tenants.
The Physical Standby Database solution in V4.1.0 has the following characteristics:
The primary and standby tenants can be deployed in the same cluster or in different clusters to implement disaster recovery at different levels.
The primary and standby tenants are independently deployed and unaware of each other. You only need to configure a log synchronization link between the primary tenant and a standby tenant. OceanBase Database V4.1.0 allows you to establish a log synchronization link only based on log archiving.
The Physical Standby Database solution supports only the maximum performance mode and no longer supports the maximum protection or maximum availability mode.
The following figure shows the deployment architecture of the Physical Standby Database solution.
