If all nodes of the primary instance in a Global Active Database (GAD) instance group for ApsaraDB RDS for MySQL are unavailable, you can perform a switchover by promoting a secondary instance in the GAD instance group to be the primary instance with a few clicks. Before the switchover, the secondary instance can process only read requests. After the switchover, the new primary instance can process read and write requests. This helps restore the workloads of your applications. This feature is suitable for scenarios such as disaster recovery (DR) drills and geo-disaster recovery switchovers.
Prerequisites
The GAD instance group is in the Running state.
The GAD instance group is a DR instance group. For more information about the differences between a DR instance group and an active geo-redundancy instance group, see DR and active geo-redundancy.
Usage notes
If you forcefully perform a primary/secondary switchover on a GAD instance group, data loss may occur. Proceed with caution. When you perform a primary/secondary switchover on a GAD instance group, transient connections may occur. We recommend that you perform the primary/secondary switchover during off-peak hours and ensure that your application is configured to automatically reconnect to the GAD instance group.
A Data Transmission Service (DTS) data synchronization task that is created for the primary and secondary instances implements one-way data synchronization. After a forceful primary/secondary switchover on a GAD instance group is complete, the original primary instance and the rest of the secondary instances in the GAD instance group are removed from the GAD instance group. In this case, the DTS data synchronization task is interrupted. Proceed with caution.
The instances removed from the GAD instance group become independent ApsaraDB RDS for MySQL instances. The independent RDS instances are not released, and the instance data and the DTS data synchronization accounts remain unchanged. You can still find the RDS instances on the Instances page.
NoteAfter the primary/secondary switchover on a GAD instance group is complete, you can re-add the removed ApsaraDB RDS for MySQL instances as secondary instances to the GAD instance group.
Procedure
Go to the Global Active Instances page.
Find the GAD instance group that you want to manage and click the instance group ID.
In the List of RDS instances section, find the required instance and click Switch To Primary Instance in the Actions column.
On the page that appears, read the impacts of a primary/secondary switchover and click Switch.
Related operations
After the primary/secondary switchover on a GAD instance group is complete, evaluate your business requirements and determine whether to change the endpoint in your application to the endpoint of the new primary instance to connect to the new primary instance.