Once the RDS instance is created successfully, the system automatically creates a free slave instance for it. The slave instance is located in the same region, where the master instance is located, but in a different zone.

The data in the master instance synchronizes to the slave instance in real time. You can only access the master instance. The slave instance exists only as a backup. However, when the rack (where the master instance is located) encounters an error, the master and slave instances can be switched. After the handover, the original master instance becomes a backup instance, and the rack-level disaster tolerance can be realized.

This document describes how to switch the master/slave instance.


  • Currently this operation is not applicable to the Basic Edition of MySQL 5.7 and SQL Server 2012/2016 instances. This is because Basic Edition instances do not have slave nodes.

  • Switching the master/slave instance may result in transient disconnection. Make sure that your application has a reconnection configuration.


  1. Log on to the  RDS console.
  2. Select the region where the target instance is located, and click the ID of a target instance.
  3. In the left-side navigation pane, select Instance Availability.
  4. In the Availability Information area, click Switch Master/Slave Instance.
  5. Select Switch now or Switch within maintenance period.
    During the switching, many operations cannot be performed. Therefore, we recommend that you choose to switch within the maintenance period.

  6. If necessary, you can change the maintenance period as follows:
    1. Click Modify to open the Basic Information page.

    2. In the Configuration Information area at the lower left corner, select a maintenance period and click Save.

    3. Go back to the page for master/slave switchover.
  7. Click OK.