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

Billing rules

For more information, see Configuration change fees.

Limits

• If the network type of an instance is classic network, you must activate the Internet for the instance or switch the instance to a virtual private cloud (VPC). This way, the number of read-only nodes in the instance is changed.

• When you change the configurations of an instance, you cannot reduce the storage capacity of the instance. To reduce the storage capacity of the instance, you can create an instance and restore data stored in the existing instance to the new instance. For more information, see Other configuration change scenarios and methods.

• When you change the configurations of an instance, the architecture or storage engine of the instance cannot be changed. For example, you cannot change a replica set instance into a sharded cluster one. To change the architecture or storage engine of the instance, you can create an instance and restore data stored in the existing instance to the new instance. For more information, see Other configuration change scenarios and methods.

Usage notes

• The amount of time required to perform a configuration change depends on factors such as the network conditions, task queue status, and data volume. We recommend that you change the configurations of an instance during off-peak hours and make sure that your application is configured to automatically reconnect to the instance.

• If you scale up only the storage capacity of a general-purpose or dedicated instance that uses local disks and resides in a physical device with sufficient resources, the scale-up is performed on the device without cross-host migration or switchover. Therefore, the configuration change is immediately applied and in effect without connection interruption at any point in time.

• If you scale up only the storage capacity of an instance that uses cloud disks, the configuration change immediately takes effect regardless of the specified maintenance window and does not cause transient disconnections.

• During a configuration change, you may experience one or two transient disconnections. Each transient disconnection lasts about 30 seconds. The Switching Time parameter specifies the time at which you want to apply the configuration change. You can set the parameter to an off-peak period of time to prevent service interruptions.

• Configuration changes do not cause data loss.

• When you change the configurations of an instance that uses local disks, the system update the minor version of the instance to the latest version by default.

Procedure

1. Go to the Replica Set Instances page. In the top navigation bar, select the region in which the instance resides. Then, find the instance and click the ID of the instance.

2. In the Specification Information section of the instance details page, perform the required operations based on the billing method of the instance.

   • Subscription instance

     In the upper-right corner of the Specifications section, click Upgrade or Downgrade.

   • Pay-as-you-go instance

     In the upper-right corner of the Specifications section, click Change Configurations.

3. Configure the parameters described in the following table.

   Type	Parameter	Description
   Upgrade Downgrade	Active-standby Nodes	The number of nodes that can be selected when you change the configurations of the instance. Valid values: Three Nodes Replicaset: cannot be downgraded. Five Nodes Replicaset: can be downgraded to Three Nodes Replicaset. Seven Nodes Replicaset: can be downgraded to Three Nodes Replicaset or Five Nodes Replicaset.
   	Read-only Nodes	The number of read-only nodes that can be selected when you change the configurations of the instance. Valid values: 0 to 5.
   	Specifications	The new specifications of the instance. For more information about the specifications supported by replica set instances, see Instance types.
   	Storage	The storage capacity that can be selected when you change the configurations of the instance. Note When you change the configurations of an instance, you cannot reduce the storage capacity of the instance. To reduce the storage capacity of the instance, you can create an instance and restore data stored in the existing instance to the new instance. For more information, see Other configuration change scenarios and methods. This parameter specifies the storage capacity of each node, but not the total storage capacity of all nodes.
   	Switching Time	The time when you want to apply the configuration change. Valid values: Switch Immediately After Data Migration: ApsaraDB for MongoDB applies the configuration change immediately after you complete configuration change settings. Switch Within Maintenance Window: ApsaraDB for MongoDB applies the configuration change within the maintenance window that you specify. You can use the current maintenance window or specify a new maintenance window by using one of the following methods: Click Modify next to Switch Within Maintenance Window. In the Specification Information section of the instance details page, click Edit next to Maintenance Window to specify a maintenance window. For more information, see Specify a maintenance window. Note If you scale up only the storage capacity of a general-purpose or dedicated instance that uses local disks and resides in a physical device with sufficient resources, the scale-up is performed on the device without cross-host migration or switchover. Therefore, the configuration change is immediately applied and in effect without connection interruption at any point in time. If you scale up only the storage capacity of an instance that uses cloud disks, the configuration change immediately takes effect regardless of the specified maintenance window and does not cause transient disconnections.

4. Read and select the Terms of Service, click Buy Now, and then complete the payment as prompted.

   When you change the configurations of the instance, the instance status is Changing Configuration. If the instance status changes to Running, the instance configurations are changed.

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