This topic describes how to change the data replication mode of an RDS for MySQL instance and its slave instance to improve service availability

This function is available to the High-availability Edition of MySQL 5.5, 5.6, and 5.7.

Note In the MySQL 5.6 or 5.7 Enterprise Edition, you cannot change the replication mode.

Overview of data replication

  • Semi-synchronous

    The updates initiated from your application are performed on the master RDS instance. Then the corresponding logs are synchronized to the slave RDS instance. The system regards that the transactions are submitted before the updates recorded in the logs are performed on the slave RDS node.

    If the slave RDS instance is unavailable or communication between the master and slave RDS instances is abnormal, the semi-synchronous data replication mode is degraded to the asynchronous data replication mode.

  • Asynchronous

    When your application initiate an update request for adding, deleting, or modifying data, the master RDS instance responds to your application immediately and replicates data to the slave RDS instance asynchronously after completing the requested operation. Therefore, in asynchronous data replication mode, the operations on the master RDS instance are not affected even when the slave RDS instance is unavailable. Additionally, the probability that data inconsistencies are incurred by unavailability of the master RDS instance is low.


The DB engine version and edition are one of the following:

  • MySQL 8.0 High-availability Edition (with local SSDs)
  • MySQL 5.7 High-availability Edition (with local SSDs)
  • MySQL 5.6 High-availability Edition
  • MySQL 5.5


  1. Log on to the RDS console.
  2. In the upper-left corner, select the region where the target RDS instance is located.选择地域
  3. Find the target RDS instance and click the instance ID.
  4. In the left-side navigation pane, click Service Availability.
  5. In the Availability Information section, click Change Data Replication Mode. 修改数据修复方式
  6. In the displayed dialog box, select a data replication mode and click OK. 选择数据复制方式


API Description
ModifyDBInstanceHAConfig Used to change the HA mode and data replication mode of an RDS instance.