The size of the system disk and data disks that have been created for an ECS instance cannot be reduced. If you need to shrink the disks, you can use the Alibaba Cloud Server Migration Center (SMC).
SMC is developed to balance cloud-based and off-cloud workloads for Alibaba Cloud users. However, it can also be used to shrink disks. When migrating an ECS instance across accounts or within the same account, SMC can migrate the instance as an image, for which you can specify a smaller value for the disk capacity of the image. Then this image can be used to create a new instance to complete the migration. For more information, see Migrate data between ECS instances that belong to the same Alibaba Cloud account or different Alibaba Cloud accounts.
Prerequisites
Complete all necessary preparations before starting the migration process. For more information, see Before you begin.
Procedure
Import the ECS instance whose disks you want to shrink as a migration source into the SMC.
For more information, see Step 1: Import the information about a migration source.
Create and start a migration job.
For more information, see Step 2: Create and start a migration job.
When setting up the migration job, set the required parameters as follows:
Destination Type: Choose ECS Image.
Destination Disk Size (GiB): Specify the new sizes for the System Disk and Data Disk, ensuring they are not less than the actual used capacities.
Verify whether the capacity and data of the migrated disks meet the expectations.
For more information about the migration result verification, see Verify the migration result.