Help Center/ Elastic Cloud Server/ User Guide/ Disks/ Attaching a Disk to an ECS
Updated on 2026-09-16 GMT+08:00
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Attaching a Disk to an ECS

Scenarios

If the existing disks of an ECS fail to meet service requirements, for example, due to insufficient disk space or poor disk performance, you can attach more available EVS disks to the ECS, or purchase more disks (choosing Storage > Elastic Volume Service) and attach them to the ECS.

When attaching EVS disks to an existing ECS, their billing modes can be different from the ECS billing mode. You can select appropriate billing modes for these EVS disks based on your requirements.

Constraints

  • Disks can be attached only when the ECS is Running or Stopped.
  • ISO images are only recommended for OS installation. Some functions are restricted and disks cannot be attached to ECSs that are created from ISO images.
  • A maximum of 60 disks can be attached to an ECS.

    The number of disks that can be attached to an ECS varies depending on the ECS flavor and disk type. For details, see Can I Attach Multiple Disks to an ECS?

  • EVS data disks can only be attached to ECSs in the same region and AZ.
  • If you have detached the system disk that was purchased along with a yearly/monthly ECS and want to use it as a system disk again, you can only attach it to the original ECS.
  • A system disk purchased together with a pay-per-use server can be re-attached as a data disk for any server after being detached. If you want to use it again as a system disk, you must attach it to a server that uses the same system disk image as the original server.
  • Frozen EVS disks cannot be attached to ECSs.
  • A shared disk can only be used as a data disk. It cannot be used as a system disk.
  • Shared EVS disks can be attached to multiple ECSs running the same type of OS (either Windows or Linux). For example:

    If a shared EVS disk is attached to multiple Windows ECSs for the first time, it cannot be attached to Linux ECSs after it is detached from Windows ECSs. This is because Windows and Linux support different file systems. Improper operations may damage the original file system.

For more details about attaching disks, see Attaching a Non-Shared Disk and Attaching a Shared Disk.

Prerequisites

Procedure

  1. Log in to the ECS console and access the ECS list page.
  2. In the search box above the ECS list, enter the ECS name, IP address, or ID for search.
  3. Click the name of the target ECS.

    The ECS details page is displayed.

  4. Click the Disks tab. Then, click Attach Disk.

    The Attach Disk dialog box is displayed.

    Figure 1 Attach Disk (KVM)
  5. Select the target disk and specify the disk as the system disk or data disk.
    • For KVM ECSs, you can specify a disk as a system disk or data disk but cannot specify a device name for the disk.
    • For Xen ECSs, you can specify the device name of a disk, such as /dev/vdb.
  6. Click OK.

    After the disk is attached, you can view the information about it on the Disks tab.

Follow-up Procedure

If the attached disk is newly created, the disk cannot be used until it is initialized.

For details about how to initialize a data disk, see Initializing Data Disks.

Parent Topic: Disks