Scale in storage capacity for an ApsaraDB RDS for MySQL cloud disk instance - ApsaraDB RDS

Prerequisites

Your ApsaraDB RDS for MySQL instance must meet the following requirements. You can view the instance details on the Basic Information page:
- Major engine version: 5.7 or 8.0
- Minor engine version: 20210430 or later.
- Storage type: ESSD or premium performance disk. Standard SSDs are not supported.
  
  Note
  If your instance uses a standard SSD, you must first upgrade it to an ESSD before you can scale in its storage capacity.
- Instance architecture: Only the new architecture (kindcode=18) is supported.
  
  Note
  You can call the DescribeDBInstanceAttribute operation to query the instance architecture. If the instance uses the old architecture (kindcode=1 or 3), you must first upgrade the minor engine version to adopt the new architecture before scaling in.
- The instance is in the Running state and the log backup feature is enabled.
Your Alibaba Cloud account has no unpaid renewal orders.

Note
If you have unpaid renewal orders, go to the ApsaraDB RDS console. In the upper-right corner, hover over Fee, and click Orders. On the Orders page, pay for or cancel the orders.
To scale in a read-only instance, its primary instance must be in the Running state.

Limitations

Scale-in frequency: You can manually scale in the storage capacity a maximum of two times per day. Avoid frequent scale-in operations to prevent service disruptions.
Scale-in conditions and formula:
- You can scale in the storage capacity only for instances of the same series and architecture.
- After a scale-in, the new storage capacity must be greater than or equal to the value from the formula min{Used storage × 1.3, Used storage + 400 GB} and cannot be less than the minimum allowed for the current instance type. The storage capacity can be adjusted in 5 GB increments.
  Minimum storage capacity for different cloud disk types and scale-in examples
  The minimum storage capacity for each cloud disk type (ESSD and premium performance disk) is as follows:
  - ESSD PL1: 20 GB
  - ESSD PL2: 500 GB
  - ESSD PL3: 1,500 GB
  - Premium performance disk: 10 GB
  Scale-in examples
  
  For example, consider an ApsaraDB RDS for MySQL instance with an original storage capacity of 2,000 GB that uses an ESSD PL1 disk (minimum capacity: 20 GB).
  - If 10 GB of storage is used: The formula returns 13 GB. Since this is less than the 20 GB minimum, the lowest capacity you can scale down to is 20 GB.
  - If 500 GB of storage is used: The formula returns 650 GB. The minimum capacity you can scale down to is 650 GB.
  - If 1,500 GB of storage is used: The formula returns 1,900 GB. The minimum capacity you can scale down to is 1,900 GB.
Primary and read-only instances: The storage capacity of a read-only instance must be greater than or equal to that of its primary instance. We recommend scaling in the storage capacity of the primary instance before the read-only instance.
Scale-in duration and service traffic: The time required for a scale-in operation depends on the used storage and service traffic. If your instance handles high service traffic, we recommend that you adjust the local log retention policy by increasing the retention period and the number of log files. This improves the efficiency and success rate of the scale-in operation.
Binlog requirements: If the Binlog of an instance grows rapidly, you must ensure that a sufficient number of logs are retained locally before you can scale in the instance. To enable log backup, see Modify an RDS backup policy.
Backup tasks: The scale-in process may cancel a running backup task. We recommend that you perform the scale-in operation after the current backup is complete.

Impact

A manual scale-in of storage capacity causes a transient connection interruption that lasts for about 15 seconds. During this period, most operations related to databases, accounts, and networks are unavailable. We recommend performing this operation during off-peak hours and ensuring your application has an automatic reconnection mechanism.

Billing

For information about billing changes, see Billing rules for instance configuration changes.

Procedure

Pay-as-you-go and subscription

Go to the ApsaraDB RDS instance list, select a region at the top of the page, and then click the ID of the target instance.
In the Configuration Information section, click Change Configurations.
(This step applies only to subscription instances.) In the dialog box that appears, click Downgrade, and then click Next.

Configure the key parameters for the scale-in operation.

Parameter	Description
Storage Type	Optional. Select a storage type as needed.
Instance type	Optional. Select an instance type as needed.
Storage capacity	Drag the slider or click the minus icon to decrease the storage capacity. Note After a scale-in, the new storage capacity must be greater than or equal to the value from the formula `min{Used storage × 1.3, Used storage + 400 GB}` and cannot be less than the minimum allowed for the current instance type. The storage capacity can be adjusted in 5 GB increments.
Switching Time	Select a switchover time as needed: Switch Immediately After Data Migration: Data migration starts immediately without affecting your instance. A switchover, which causes a transient connection interruption, occurs upon completion. Switch Within Maintenance Window: Data migration starts immediately without affecting your instance. The switchover, which causes a transient connection interruption, occurs during the specified maintenance window.

Read and accept the terms of service, and click Pay Now. In the dialog box that appears, confirm the instance information before and after the change, and then click Continue to complete the payment.

Serverless

Go to the ApsaraDB RDS instance list, select a region at the top of the page, and then click the ID of the target instance.
On the Basic Information page of the instance, in the Instance Resources section, click Modify to the right of Storage Capacity.
In the panel that appears, click the minus icon to decrease the storage capacity, and then click OK. In the dialog box that appears, click Confirm.

Note

A scale-in operation requires data copying and takes several minutes, making it longer than a scale-out operation. During a scale-in or scale-out process, the instance state is Changing Configuration. After the process is complete, the instance state changes to Running.

FAQ

Q: How long does the transient connection interruption last during a manual storage scale-in for an ApsaraDB RDS for MySQL instance that uses a cloud disk?

A: The operation causes a transient connection interruption that lasts for about 15 seconds. During this period, most operations related to databases, accounts, and networks are unavailable. We recommend performing this operation during off-peak hours and ensuring your application has an automatic reconnection mechanism.
Q: How do I scale in the storage capacity of an ApsaraDB RDS for MySQL instance that uses a standard SSD?

A: You cannot scale in the storage capacity of instances that use standard SSDs. In addition, standard SSDs are discontinued. You must upgrade the standard SSD to an ESSD and then follow the instructions in this topic to scale in the storage capacity.

ApsaraDB RDS:Scale in storage capacity for an ApsaraDB RDS for MySQL cloud disk instance