Scale in the storage capacity of an ApsaraDB RDS for MySQL instance that uses cloud disks to reduce resource waste and lower costs. During the same operation, you can also downgrade the performance level (PL) of an enterprise SSD (ESSD) and the instance type.
Prerequisites
Before you begin, make sure your instance meets all of the following requirements. Check the Basic Information page for instance details.
Instance requirements:
Major engine version: 5.7 or 8.0
Minor engine version: 20210430 or later
Storage type: enterprise SSD (ESSD) or premium performance disk — standard SSDs are not supported
NoteIf your instance uses a standard SSD, upgrade it to an ESSD first.
Instance architecture: new architecture (kindcode=18) only
NoteCheck the architecture using the DescribeDBInstanceAttribute API. If the instance uses the old architecture (kindcode=1 or 3), upgrade the minor engine version first.
Instance status: Running, with log backup enabled
Account requirements:
No unpaid renewal orders on your Alibaba Cloud account
NoteTo clear unpaid orders, go to the ApsaraDB RDS console, hover over Expense in the upper-right corner, and click Orders. On the Orders for Services page, pay for or cancel the orders.
For read-only instance scale-in: the primary instance must be Running
Limitations
Scale-in frequency
Scale in storage capacity up to twice per day. Avoid frequent scale-ins to prevent service disruptions.
Minimum storage after scale-in
The minimum storage capacity you can scale down to is determined by:
min{current usage × 1.3, current usage + 400 GB}The result must also be no less than the disk type's absolute minimum. Storage capacity adjusts in 5 GB increments. Scale-in is supported only within the same series and architecture.
Absolute minimums by disk type:
Disk type | Minimum capacity |
PL1 ESSD | 20 GB |
PL2 ESSD | 500 GB |
PL3 ESSD | 1,500 GB |
Premium performance disk | 10 GB |
Example: An instance uses a PL1 ESSD (minimum: 20 GB) with 2,000 GB allocated.
Used storage | Formula result | Minimum you can scale down to |
10 GB | 13 GB (below 20 GB floor) | 20 GB |
500 GB | 650 GB | 650 GB |
1,500 GB | 1,900 GB | 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. Scale in the primary instance before scaling in the read-only instance.
Backup jobs
A scale-in operation may cancel a running backup job. Start the scale-in after the current backup completes.
Binary log requirements
If an instance generates binary logs at a high rate, make sure enough logs are retained locally before starting a scale-in. To adjust the log retention policy, see Modify RDS backup policy.
Scale-in duration
The time required depends on disk usage and service traffic. If your instance handles high service traffic, increase the local log retention period and the number of retained log files to improve the efficiency and success rate of the operation.
Billing
For details on pricing changes, see Billing rules for upgrades/downgrades.
Impact
A storage scale-in causes a transient connection that lasts about 30 seconds. During the transient connection, most operations related to databases, accounts, or networks are unavailable. Perform the scale-in during off-peak hours and make sure your application has an automatic reconnection mechanism configured.
The instance status shows Upgrading during the operation and returns to Running when complete. Scale-in involves data copying and takes several minutes — longer than a scale-out.
Billing
For billing changes that result from a scale-in, see Billing rules for upgrades/downgrades.
Scale in storage capacity
Pay-as-you-go and subscription instances
Go to the RDS instance list, select a region, and click the target instance ID.
In the Configuration Information section, click Change Specifications.
(Subscription instances only) In the dialog box that appears, click Downgrade, then click Next.
Set the following parameters:
Parameter
Description
Storage type
(Optional) Select a storage type.
Instance type
(Optional) Select an instance type.
Storage capacity
Move the slider or click the minus icon to decrease storage. The new capacity must satisfy
min{current usage × 1.3, current usage + 400 GB}and cannot be less than the disk type's minimum. Capacity adjusts in 5 GB increments.Switching time
Select when to perform the switchover: Switch Immediately After Data Migration starts migration immediately and switches over when migration completes. Switch Within Maintenance Window starts migration immediately but delays the switchover until the maintenance window. Both options cause a transient connection at switchover.
Read and accept the Terms of Service, then click Confirm Order. Review the before-and-after instance configuration, click Continue, and complete the payment.
Serverless instances
Go to the RDS instance list, select a region, and click the target instance ID.
On the Basic Information page, in the Instance Resources section, click Modify next to Storage Capacity.
Click the minus icon to decrease storage capacity, click OK, then click Confirm.
FAQ
Why is my scale-in blocked or showing a higher minimum than expected?
The minimum storage you can scale down to is min{current usage × 1.3, current usage + 400 GB}, and it can never be less than the disk type's absolute minimum (for example, 20 GB for a PL1 ESSD). If your used storage is high, the formula result will be high. To scale down further, reduce the data stored on the instance first, then retry.
How do I scale in a standard SSD instance?
Standard SSDs do not support storage scale-in. . — upgrade to an ESSD first, then follow the steps in this topic.
What's next
Scale in via API: call ModifyDBInstanceSpec with
DBInstanceStorageset to the target capacityScale in storage for instances using high-performance local disks