Overview

OceanBase Database provides three protection modes.

Protection modes

OceanBase Database provides the following three protection modes:

• MAXIMUM PERFORMANCE

  This is the default protection mode.

  It protects user data and maximizes the performance of the primary cluster. In this protection mode, a transaction can be committed immediately after the persistence of REDO logs in the primary cluster is complete. REDO logs are asynchronously transferred to standby clusters, without affecting the transaction commits in the primary cluster. Therefore, the performance of the primary cluster is not affected by the synchronization latency of standby clusters.

• MAXIMUM PROTECTION

  This protection mode maximizes data protection to prevent data loss when the primary cluster fails. In this protection mode, a transaction can be committed only after the persistence of REDO logs in the primary cluster and the standby cluster that is in SYNC mode is complete.

  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, a transaction can be committed only after the persistence of REDO logs in the primary cluster and the standby cluster that is in SYNC mode is complete. However, when a failure of the standby cluster in SYNC mode is detected, the primary cluster no longer waits for the synchronization to complete. Instead, the services of the primary cluster are recovered 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 recovered, the primary cluster automatically resumes the SYNC mode 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.

Limitations

Take note of the following limitations on protection modes:

• The MAXIMUM PERFORMANCE, MAXIMUM PROTECTION, and MAXIMUM AVAILABILITY modes are supported.

• The configurations of standby clusters in MAXIMUM PROTECTION or MAXIMUM AVAILABILITY mode are subject to the following limitations:

  • You have one standby cluster in SYNC mode.

  • The standby cluster in SYNC mode cannot be modified, deleted, or disabled.

  • The log transfer mode of the standby cluster in SYNC mode must not be changed to ASYNC.

• Switchovers in MAXIMUM PROTECTION or MAXIMUM AVAILABILITY mode are subject to the following limitations:

  • Only the standby cluster in SYNC mode can be switched to the primary role.

  • The log transfer mode of the primary cluster must be set to SYNC to ensure that it is in MAXIMUM PROTECTION mode after a primary/standby switchover.