Changing Instance vCPUs and Memory

Scenarios

You can change the vCPUs and memory of your instance.

Constraints

• Ensure that your account balance is greater than or equal to $0 USD.
• An instance cannot be deleted while its vCPU or memory specifications are being changed.
• If the underlying ECS uses an architecture different from that of the target instance class, the instance class cannot be changed and a message will be displayed, indicating that instance class changes between the QingTian architecture and non-QingTian architecture are not allowed. For details, see Modifying Specifications of Individual ECSs.
• The dedicated instance class cannot be changed to any other instance class. For example, a general-purpose instance can be changed to a dedicated instance, but a dedicated instance cannot be changed to a general-purpose instance.
• You can scale up or down the compute and memory capacity of RDS for SQL Server DB instances as needed.
• RDS for SQL Server supports automatic instance class restoration. If you scale up the vCPUs and memory of your instance and specify a restoration time, the instance class will be restored to the status before the scale-up at the specified time (storage space is not restored). To use this function, submit a service ticket to request required permissions.
• If you have selected During maintenance window for Scheduled Time, the DB instance will be rebooted during the instance class change time and services will be interrupted. You are advised to set the maintenance window to off-peak hours.
• After you change instance classes, the DB instances will be rebooted and services will be interrupted. You are advised to perform this operation during off-peak hours.

Change Duration and Impact

Changing an instance class will interrupt workloads. The following lists the time required for this change and the estimated downtime during off-peak hours:

• Single-node instance: The change takes 5 to 15 minutes, during which workloads are interrupted once for 1 to 2 minutes.
• Primary/standby instance: The change takes 10 to 20 minutes, during which workloads are interrupted twice, each for 1 to 2 minutes.
• Cluster instance: The change takes 10 to 20 minutes, during which workloads are interrupted twice, each for 1 to 2 minutes.

Instance Class Type Change

General-purpose instances can be changed to dedicated instances, but dedicated instances cannot be changed to general-purpose.

Related Parameters

The max server memory parameter is automatically updated after a specification change. You are advised to adjust its value based on the following formula: Value = Memory size (GB) x 1024 x 0.85 – 1.5 x 1024. For example, if the instance memory is 4 GB, set max server memory to 1946 MB (4 x 1024 x 0.85-1.5 x 1024).

Procedure

1. Log in to the RDS console.
2. Click in the upper left corner and select a region.
3. 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 Summary page. Under Instance Class, click Configure.

4. On the displayed page, specify the new instance specifications and scheduled time and then click Next.
   Figure 1 Changing the instance specifications
   

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

   Specify the Scheduled Time field:

   • If you select Immediate, the change is applied immediately after the request is submitted.

     RDS for SQL Server supports automatic specification restoration. You can select Auto Restore and specify a restoration time when changing the specifications. At the specified time, the new specifications will be automatically restored to the original configuration. To use this function, submit a service ticket to request permissions.

   • If you select During maintenance window, the instance will be rebooted during the change and workloads will be interrupted. After you submit the request, you can view the task on the Task Center > Scheduled Tasks page. For details, see Viewing a Task. Set the maintenance window to off-peak hours.

     Once you submit the request to change specifications during a maintenance window, the task cannot be canceled or modified.

5. 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 specification change, choose Billing & Costs > Bills in the upper right corner.

   • For yearly/monthly DB instances:
     • If you intend to downgrade the specifications, 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 upgrade the specifications, click Pay Now. The change starts only after the payment is successful.

6. Check the change result.

   Return to the Instances page and view the instance status. During the change, the instance remains in the Changing instance class state. After a few minutes, click the instance name to go to the Summary page and verify the new instance specifications.