Changing a DB Instance Type from Single-Node to Primary/Standby

Scenarios

RDS enables you to change single-node DB instances to primary/standby DB instances to improve instance reliability.

The time required for changing an instance type from single-node to primary/standby depends on the amount of data to be backed up. Changing a single-node instance to a primary/standby instance does not affect workloads on the instance.

Instance Architecture

A single-node instance has only one database node. If a single-node instance fails, it cannot recover in a timely manner.

A primary/standby instance uses an HA architecture with a primary node and a standby node. If a VM, hard disk, or network fault occurs on the primary node, a failover is triggered and the standby node quickly takes over workloads.

Figure 1 Topology

Precautions

• RDS single-node DB instances can be changed to primary/standby DB instances, but not the other way around.
• Changing a single-node instance to primary/standby does not change its networking information, including the VPC, subnet, security group, floating IP address, private domain name, and database port.

Procedure

1. Log in to the management console.
2. Click in the upper left corner of the page and choose Databases > Relational Database Service.
3. On the Instances page, locate a single-node DB instance and choose More > Change Type to Primary/Standby in the Operation column.
4. Select a standby AZ. Other configurations are the same as those of the primary DB instance by default. Confirm the configurations and click Submit.

   For yearly/monthly DB instances, click Pay Now.

5. Check the instance status on the Instances page.
   • The DB instance is in the Changing type to primary/standby status. You can view the task progress (not the time progress) on the Task Center page. For details, see Task Center.
   • In the upper right corner of the DB instance list, click to refresh the list. After the DB instance type is changed to primary/standby, the instance status will change to Available and the instance type will change to Primary/Standby.