Help Center/ Relational Database Service/ User Guide/ Working with RDS for SQL Server/ Instance Modifications/ Changing a DB Instance Class
Updated on 2025-11-26 GMT+08:00
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Changing a DB Instance Class

Scenarios

You can change the instance class (vCPUs and memory) of a DB instance as required.

Constraints

  • An instance cannot be deleted while its instance class is being changed.
  • 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 on Workloads

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.

Procedure

  1. Log in to the management console.
  2. Click in the upper left corner of the page and choose Databases > Relational Database Service.
  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 Overview page. Under Instance Class, click Configure.

  4. On the displayed page, specify the new instance class and click Next.
  5. Check the change result.

    Changing the DB instance class takes 5–15 minutes. During this period, the status of the DB instance on the Instances page is Changing instance class. After a few minutes, click the instance name and view the instance class displayed on the Overview page to check that the change is successful.

    After you change the instance class of an RDS for SQL Server instance, the value of max server memory will be changed accordingly. You are advised to set max server memory to Memory size (GB) x 1024 x 0.85 – 1.5 x 1024. For example, if your memory is 4 GB, set max server memory to 1946 MB (4 x 1024 x 0.85-1.5 x 1024).

Parent Topic: Instance Modifications