ApsaraDB for MongoDB:Change the configurations of a replica set instance

Limitations

• To change the number of Read-only Nodes on a Classic Network instance, first enable public access or switch to a virtual private cloud (VPC).

• Storage can only be increased, not reduced. To reduce storage, create a new instance and migrate your data. For more information, see Other configuration change scenarios and methods.

• Instance type and storage class cannot be changed. For example, a replica set instance cannot be converted to a sharded cluster instance. To switch instance type or storage class, create a new instance. For more information, see Other configuration change scenarios and methods.

Impacts

Before you change instance configurations, review the following impacts:

• Transient disconnections: A configuration change may cause one or two transient disconnections, each lasting approximately 30 seconds. Schedule changes during off-peak hours, and make sure your application supports automatic reconnection.

• Storage-only scale-out (no interruptions):

  • Local disks (general-purpose or dedicated): If you only increase storage and the host machine has enough resources, the scale-out runs locally without migration or switchover. The change takes effect immediately with no connection interruptions, regardless of the Switching Time setting.

  • Cloud disks: If you only increase storage, the change takes effect immediately with no connection interruptions, regardless of the Switching Time setting.

• Minor version upgrade: When you change the configurations of an instance that uses local disks, the system, by default, upgrades the minor database version to the latest version.

• No data loss: Configuration changes do not cause data loss.

Change instance configurations

1. Go to the MongoDB replica set instances page. At the top of the page, select a resource group and a region, and then click the target instance ID.

2. In the Specification Information section, open the configuration change page:

   • Subscription instance: In the upper-right corner, click Upgrade or Downgrade. If you click Downgrade, confirm the refund notice in the dialog box that appears.

   • Pay-as-you-go instance: In the upper-right corner, click Change Configurations.

3. On the configuration change page, set the following parameters.

   Note

   For storage-only scale-outs, the change takes effect immediately regardless of the Switching Time setting. For details, see Impacts.

   Parameter	Description
   Active-standby Nodes	Select the number of primary and secondary nodes. Valid values: Three Nodes Replicaset (downgrade not supported), Five Nodes Replicaset (can downgrade to Three Nodes Replicaset), and Seven Nodes Replicaset (can downgrade to Three Nodes Replicaset or Five Nodes Replicaset).
   Read-only Nodes	Select the number of read-only nodes. Valid values: 0 to 5.
   Category	Select General-purpose or Dedicated.
   Specifications	Select the target specifications. For available options, see Instance types.
   Storage	Select the new storage capacity. The value applies to each node individually, not the total across all nodes. Storage cannot be reduced. To reduce storage, see Limitations.
   Switching Time	Select when the configuration change takes effect. Switch Immediately After Data Migration: the change applies as soon as data migration completes. Switch Within Maintenance Window: the change applies during the next maintenance window. To modify the maintenance window, click Modify next to Switch Within Maintenance Window, and then click Edit next to Maintenance Window in the Specification Information section. For more information, see Set a maintenance window.

4. Read the Terms of Service, click Buy Now, and complete the payment.

Verify the result

After you submit the configuration change, the instance status changes to Modifying. When the status returns to Running, the configuration change is complete.

Billing

For billing details, see Configuration change fees.

API reference