Changing a Replica Set Instance Class

Precautions

• A DB instance cannot be deleted while its instance class is being changed.
• When the CPU or memory of a replica set instance is changed, the read replica class is not changed.
• When the instance class is being changed, a primary/secondary switchover may occur once or twice and the database connection will be interrupted each time for up to 30s. You are advised to change the class during off-peak hours to reduce impacts and ensure that the service system of your client can reconnect to the database if the connection is interrupted.
• After the class of a replica set instance is changed, the system will change the value of net.maxIncomingConnections accordingly.
• If you forcibly change the class of an abnormal node in a DB instance, services may be interrupted.

Pre-check Items for Instance Class Change

• The instance status and the status of the node whose class is to be changed are normal.
• The primary/standby replication delay does not exceed 20s.

Changing the Class of a Replica Set Instance

1. Log in to the management console.
2. Click in the upper left corner and select a region and a project.
3. Click Service List. Under Database, click Document Database Service to go to the DDS console.
4. On the Instances page, locate the replica set instance and choose More > Change Instance Class in the Operation column.

   Alternatively, on the Instances page, click the name of the replica set instance. In the DB Information area on the Basic Information page, click Change to the right of the Node Class field.

5. On the displayed page, select the required specifications and new instance class and click Next.
   Note

   The time required depends on the number of instance nodes whose class is to be changed. It takes about 5 to 10 minutes for each node. When the instance class is being changed, a primary/secondary switchover may occur once or twice and the database connection will be interrupted each time for up to 30s. Before the class change, learn about Pre-check Items for Instance Class Change. You are advised to change the class during off-peak hours to reduce impacts and ensure that the service system of your client can reconnect to the database if the connection is interrupted.

6. On the displayed page, confirm the instance class.
   • If you need to modify your settings, click Previous to go back to the page for you to specify details.
   • If you do not need to modify your settings, click Submit to change the instance class.

7. View the results.
   • When the instance class is being changed, the status displayed in the Status column is Changing instance class. This process takes about 25 to 30 minutes.
     Note

     High database load increases the class change duration. You are advised to change the class during off-peak hours to reduce impacts.

   • In the upper right corner of the instance list, click to refresh the list. The instance status changes to Available.
   • Go to the Basic Information page of the replica set instance you scaled up and check whether the scaling up is successful in the DB Information area.

Changing the Class of a Read Replica

1. Log in to the management console.
2. Click in the upper left corner and select a region and a project.
3. Click Service List. Under Database, click Document Database Service to go to the DDS console.
4. On the Instances page, locate the target replica set instance and click its name.
5. In the Node Information area on the Basic Information page, click the Read replicas tab. Locate the read replica whose class you want to change, and click Change Instance Class in the Operation column.
6. On the displayed page, select the required specifications and new class and click Next.
   Note

   When the class of a read replica is being changed, there is a possibility that database access requests using the read replica fail. Before the class change, learn about Pre-check Items for Instance Class Change. You are advised to change the class during off-peak hours to reduce impacts and ensure that the service system of your client can reconnect to the database if the connection is interrupted.

7. On the displayed page, confirm the class.
   • If you need to modify your settings, click Previous to go back to the page for you to specify details.
   • If you do not need to modify your settings, click Submit to change the class.

8. View the results.
   • When the class is being changed, the status displayed in the Status column is Changing instance class. This process takes about 25 to 30 minutes.
   • In the upper right corner of the instance list, click to refresh the list. The instance status changes to Available.
   • In the Node Information area on the Basic Information page, click the Read replicas tab. Locate the target read replica to view the new class.