Changing a Single-Node Read Replica to an HA Read Replica

Scenarios

You can change a single-node read replica to an HA read replica as needed. This operation does not affect your workloads.

A single-node read replica has only one physical node. If it fails, it cannot recover in a timely manner. However, an HA read replica has one primary node and one standby node. If the physical server where the primary read replica is located fails, the standby read replica automatically takes over workloads from the primary read replica. For more information, see Introduction to Read Replicas.

Constraints

• If you want to change a single read replica to an HA read replica, the single read replica must use Cloud SSD as its storage type.
  • Cloud SSD: General-purpose, dedicated, and Kunpeng general-enhanced instance classes are supported.

• If you are a DeC user, you can create HA read replicas or change single read replicas to HA read replicas. When you select DSS for Resource Type, only the storage type that you have selected when buying the DSS service is displayed by default.
• To change a single read replica to an HA read replica, ensure that the SSL certificate, disk encryption, port, and subnet of the single read replica are the same as an existing HA read replica, or your primary instance if no HA read replica has been created.
• Ensure that the subnet where your instance is located has sufficient IP addresses (≥ 3) to be assigned to HA read replicas.
• To ensure reliable operation of your workloads, do not modify parameters of HA read replicas.
• For an HA read replica, do not change its port or change it to a single read replica.

Changing to an HA Read Replica

A single read replica can be changed to an HA read replica, but an HA read replica cannot be changed to a single read replica.

1. Log in to the management console.
2. Click in the upper left corner and select a region.
3. Click in the upper left corner of the page and choose Databases > Relational Database Service.
4. In the DB instance list, click in front of the DB instance and click the target read replica name.
5. On the Overview page, find DB Instance Type and click Change to HA Read Replica.
   Figure 1 DB information
   

6. On the displayed page, confirm the information and click Submit.
   Figure 2 Changing to an HA read replica