Changing a DB Instance Class

Scenarios

You can change the instance class (vCPU or memory) of a DB instance as required. If the status of a DB instance changes from Changing instance class to Available, the change is successful.

Constraints

• You can change the DB instance class only when your account balance is greater than or equal to $0 USD.
• An instance cannot be deleted while its instance class is being changed.
• The following operations cannot be performed on an instance whose instance class is being changed: rebooting the instance, scaling up storage space, modifying the parameter template, creating a manual backup, creating a database account, and creating a database.
• You can scale up or down your RDS for MySQL instance specifications.
• When the instance class of a read replica is being changed, binlog clearing of the primary instance is disabled.
• Changing the instance class will temporarily occupy IP addresses, and the IP addresses will not be released until 12 hours later by default. Before changing an instance class, ensure that there are available floating IP addresses (two for a primary/standby instance and one for a single instance or read replica) in the subnet. Otherwise, the change will fail.
• If there are any large transactions being processed during an instance class change, the change may fail.
• If the primary/standby replication delay of a DB instance is longer than 5 minutes, the instance class change will fail.
• Changing an instance class will interrupt services for about 10 to 120 seconds. Ensure that your applications support automatic reconnection. Perform this operation during off-peak hours because changing an instance class during peak hours takes much more time.
• The time required for changing an instance class (during off-peak hours) is as follows:
  • For an instance using a cloud disk, the process takes 5 to 15 minutes.
  • If the change takes an extended period of time, contact customer service.
• If you choose to change an instance class during the maintenance window, after the request is submitted, you can locate the scheduled task and click Execute Now in the Operation column. (If this option is not displayed on the console, contact customer service.) The time required for changing an instance class can be a little bit long during peak hours due to high replication delay.

Instance Class Type Change

You can change a general-purpose instance to a dedicated instance, and vice versa. However, changing a dedicated instance to a general-purpose instance may compromise database performance. Exercise caution when performing this operation.

Billing

Parameter Changes

Memory-related parameters, such as innodb_buffer_pool_size, innodb_log_buffer_size, innodb_log_files_in_group, max_connections, innodb_page_cleaners, innodb_buffer_pool_instances, and back_log, will be reset according to the following rules during an instance class change.

However, values of innodb_io_capacity and innodb_io_capacity_max will be reset to the default values of the new instance class if no custom values have been specified for them or they will remain unchanged if you have specified custom values for them.

Procedure

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. On the Instances page, locate the target DB instance and choose More > Change Instance Class in the Operation column.

   Alternatively, click the instance name to go to the Overview page. Under Instance Class, click Configure.

5. On the displayed page, specify the new instance class and click Next.

   For RDS for MySQL DB instances billed on the pay-per-use basis, choose a new instance class and a scheduled time, and click Next.

   Figure 1 Changing a DB instance class
   

   DB instances in a DCC only support the general-enhanced instance class.

   • Upon submission: An instance class change is applied immediately after the request is submitted.
   • Maintenance Window: If you select Maintenance Window for Scheduled Time, after the request is submitted, you can locate the scheduled task and click Execute Now in the Operation column as required. (If this option is not displayed on the console, contact customer service to obtain required permissions.) For details about how to view a task, see Viewing a Task. Services are temporarily interrupted during an instance class change. You are advised to set the maintenance window to off-peak hours.

6. Confirm the specifications.
   • If you need to modify your settings, click Previous.
   • For pay-per-use DB instances, click Submit.

     To view the cost incurred by the DB instance class change, choose Billing & Costs > Bills in the upper right corner.

   • For yearly/monthly DB instances:
     • If you intend to scale down the DB instance class, click Submit.

       The refund is automatically returned to your account. You can click Billing in the upper right corner and then choose Orders > My Orders in the navigation pane on the left to view the details.

     • If you intend to scale up the DB instance class, click Pay Now. The scaling starts only after the payment is successful.

7. Check the change result.

   Return to the Instances page and view the instance status. During the change period, the instance status is Changing instance class. You can view the execution progress of Changing a MySQL DB instance class on the Task Center page. After a few minutes, view the DB instance class on the Overview page to check that the change is successful.

   For DB instances using cloud disks, if you have selected Maintenance Window for Scheduled Time, the status of the DB instance on the Instances page is Changing instance class in the maintenance window.