OceanBase Database provides three protection modes: maximum performance, maximum protection, and maximum availability. You can switch among the three modes.
Maximum performance
It is the default protection mode. It protects user data and maximizes the performance of the primary cluster. In this mode, OceanBase immediately commits transactions after REDO logs are persisted in the primary cluster. OceanBase asynchronously synchronizes REDO logs to the standby clusters without blocking the transaction commit of the primary cluster. Therefore, the performance of the primary cluster is not affected by the synchronization latency of standby clusters.
Maximum protection
This mode provides the highest level of data protection and prevents data loss when the primary cluster fails. In this mode, transactions can be committed only after the successful persistence of REDO logs on the primary cluster and the standby cluster in SYNC mode.
In this protection mode, you can configure only one standby cluster in SYNC mode, and other standby clusters must be in ASYNC mode. If the standby cluster in SYNC mode is unavailable, the primary cluster stops the write service.
Maximum availability
This protection mode maximizes data protection without compromising cluster availability. By default, transactions can be committed only after the successful persistence of REDO logs on the primary cluster and the standby cluster in SYNC mode. However, if the primary cluster detects a failure of the standby cluster in SYNC mode, the primary cluster no longer waits for the synchronization to complete. Instead, the services of the primary cluster are resumed in the same way as that in maximum performance mode to ensure the availability of the cluster. After the services of the standby cluster in SYNC mode are resumed, the primary cluster continues to synchronously transfer REDO logs to this standby cluster to provide maximum data protection.
In this protection mode, you can configure only one standby cluster in SYNC mode, and other standby clusters must be in ASYNC mode.