Help Center > > User Guide> Working with RDS for MySQL> Instance Modifications> Changing a DB Instance Class

Changing a DB Instance Class

Updated at: Jan 07, 2022 GMT+08:00


You can change the instance class (CPU 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.


  • 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 parameter groups, creating a manual backup, creating a database account, and creating a database.
  • When you change the instance class of a MySQL DB instance using local disks, the storage space after the change cannot be less than that of the original DB instance.
  • After the instance class is changed, some parameters are automatically changed to the default values defined in the new instance class. The parameters are threadpool_size, innodb_buffer_pool_size, innodb_io_capacity, innodb_io_capacity_max, innodb_buffer_pool_instances, back_log, and max_connections.
  • After you change instance classes, the DB instances will reboot and services will be interrupted. Therefore, you are advised to change instance classes during off-peak hours.
  • The instance class change performed within the maintenance period cannot be canceled.


  1. Log in to the management console.
  2. Click in the upper left corner and select a region and a project.
  3. Click in the upper left corner of the page and choose Database > Relational Database Service. The RDS console is displayed.
  4. On the Instance Management page, locate the target DB instance and choose More > Change Instance Class in the Operation column.

    Alternatively, click the target DB instance to go to the Basic Information page. In the DB Information area, click Change in the Instance Class field.

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

    Figure 1 Changing a DB instance class

    You can change the DB instance class as required.

    Changing the DB instance class will cause the DB instance to reboot. Select off-peak hours to avoid service interruptions.

    If you have selected In maintenance window for Scheduled Time, the DB instances will be rebooted during the instance class change time and services will be interrupted. To prevent service interruptions, you are advised to set the maintenance window to off-peak hours. For details, see Changing the Maintenance Window.

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

  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 Center > My Orders 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 choose Billing Center > My Orders in the upper right corner to check the refund.

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

  7. View the DB instance class change result.

    After the task is submitted, you can view the execution progress of Changing a MySQL DB instance class on the Task Center page. The status of the DB instance on the Instance Management page is Changing instance class. After a few minutes, click the DB instance and view its instance class on the displayed Basic Information page to check that the change is successful.

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

    Changing the instance class takes 5 to 15 minutes. Service downtime only occurs during the primary/standby switchover.

    After you change a MySQL instance class, the values of the following parameters will be changed accordingly: back_log, innodb_buffer_pool_size, innodb_log_buffer_size, innodb_log_files_in_group, max_connections, innodb_page_cleaners, innodb_buffer_pool_instances, threadpool_size, and slave_parallel_workers.

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