ApsaraDB RDS:Query and change data replication mode

Data replication modes

• MGR (MySQL Group Replication)

  MGR is based on the Paxos distributed consensus protocol. The primary node sends transaction data to secondary nodes. The primary node can commit the transaction only after a majority of secondary nodes acknowledge its receipt. Compared with semi-synchronous or asynchronous replication, MGR provides strong data consistency and higher data security. For more information, see Introduction to MGR.

  Important

  MySQL 8.4 does not support MGR. It supports only semi-synchronous and asynchronous replication.

• Semi-synchronous

  When an application completes an update on the primary instance, the primary instance synchronously transfers the binary log to the secondary instance. A transaction is considered committed once the secondary instance receives the binary log, without waiting for the secondary instance to replay it.

  If a secondary instance becomes unavailable or a network exception occurs between the primary and secondary instances, semi-synchronous replication degrades to asynchronous replication.

• Asynchronous

  When an application sends an update request (such as an insert, delete, or update operation), the primary instance completes the operation and immediately responds to the application. It then asynchronously replicates the data to the secondary instance. Therefore, in asynchronous replication mode, the unavailability of a secondary instance does not affect operations on the primary instance. However, if the primary instance fails, data inconsistency may occur between the primary and secondary instances.

Supported modes by RDS edition

Query data replication mode

1. Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.

2. In the navigation pane on the left, click Service Availability.

3. In the Instance Availability section, find the value for Data Replication Mode.

   

Change data replication mode

1. Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.

2. In the navigation pane on the left, click Service Availability.

3. In the Instance Availability section, click Change Data Replication Mode.

4. In the dialog box that appears, select a data replication mode and click OK.

   

   Note

   For RDS Cluster Edition instances, you can also change the data replication mode in the instance topology diagram on the Basic Information page.

FAQ

• Which data replication mode should I use?

  If you require strong data consistency and finance-grade reliability, we recommend MGR, which is supported only by RDS Cluster Edition instances. If you require extremely fast response times, use the asynchronous mode. In other scenarios, the semi-synchronous mode offers a balanced solution.

• Why can't I change the data replication mode for my instance?

  Each RDS edition supports different data replication modes. See the Supported modes by RDS edition table for details.

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