Help Center/ Elastic Volume Service/ User Guide/ Detaching and Deleting an EVS Disk/ Detaching an EVS Disk
Updated on 2026-05-11 GMT+08:00
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Detaching an EVS Disk

Scenarios

Disk Function

Server Status

Scenarios

System disk

Only offline detachment is supported.

You can only detach a system disk when the server status is Stopped.
  • If the file system on your system disk is damaged and the server cannot be started, you can detach the system disk and attach it to another server as a data disk. After the file system is fixed, you can re-attach the disk to the original server as the system disk.
  • If you no longer need a system disk or want to replace it with a new one, you can detach it.

Data disk

Both online detachment and offline detachment are supported.

You can detach a data disk when the server status is Stopped or Running.
  • If you want to use a data disk on another server in the same region and AZ, you can detach it and then attach it to that server.
  • If a data disk is no longer required, you can detach it and then delete it.
  • For an attached system disk, the disk function is displayed as System disk, and the disk status is displayed as In-use in the disk list. After the system disk is detached, the disk function changes to Bootable disk, and the status changes to Available.
  • Bootable disks are system disks that have been detached from servers. A bootable disk can be re-attached to a server to be used as a system disk or data disk depending on the disk function selected.
  • For an attached data disk, the disk function is displayed as Data disk, and the disk status is displayed as In-use in the disk list. After the data disk is detached, the disk function remains unchanged, and the status changes to Available. For a shared disk, the status changes to Available only after it is detached from all its servers.

Billing

A detached EVS disk will not be automatically deleted, so it will still be billed, as described in Billing for EVS Disks. If you no longer need a disk, delete or unsubscribe from it in a timely manner.

Constraints

  • After a system disk is detached, some operations cannot be performed on the original server and the system disk. The unsupported operations are as follows:
    • Server: starting the server, remote login, resetting the password, changing the server billing mode, changing server specifications, changing the OS, reinstalling the OS, creating images, creating backups, adding disks, changing the security group, and changing the VPC
    • System disk: changing disk billing mode
  • A shared data disk can be detached from ECSs in a batch.

Prerequisites

  • Before detaching an EVS disk from a running Windows server, ensure that no programs are reading data from or writing data to the disk. Otherwise, data will be lost.
  • Before detaching an EVS disk from a running Linux server, you must log in to the server and run the umount command to cancel the association between the disk and the file system, and ensure that no programs are reading data from or writing data to the disk. Otherwise, you will not be able to detach the disk.
  • You are advised to back up data. You can create snapshots or use CBR to create disk backups.
  1. Sign in to the ECS console.
  2. In the ECS list, locate the row that contains the target ECS, click More in the Operation column, and choose Stop.

    When the ECS status changes to Stopped, the ECS has been stopped.

  3. Click the name of this ECS.

    The ECS details page is displayed.

  4. Click the Disks tab to view the system disk attached to the ECS.
  5. Locate the row that contains the system disk and click Detach.

    The Detach Disk dialog box is displayed.

  6. Click Yes to detach the disk.

    After the operation succeeds, the detached system disk is no longer displayed under the Disks tab.

  7. (Optional) Re-attach the bootable disk to another server. You can use it as a system disk or data disk depending on the disk function you select.
  1. Sign in to the EVS console.
  2. Choose a way to detach the disk by determining whether you want to check the server information first.

    • If yes, perform the following procedure:
      1. In the disk list, click the name of the to-be-detached disk.

        The disk details page is displayed.

      2. Click the Servers tab to view the server where the disk has been attached.
      3. Click to select the server and click Detach Disk.

        The Detach Disk dialog box is displayed.

      4. Click Yes to detach the disk.
    • If no, perform the following procedure:
      1. In the disk list, locate the row that contains the target disk and choose More > Detach in the Operation column.

        The Detach Disk dialog box is displayed.

      2. Click Yes to detach the disk.

    In the disk list, the disk status is Detaching, indicating that the disk is being detached from the server.

    When the status changes to Available, the disk has been detached.

  1. Sign in to the EVS console.
  2. Choose a way to detach the disk by determining whether you want to check the server information first.

    • If yes, perform the following procedure:
      1. In the disk list, click the name of the to-be-detached disk.

        The disk details page is displayed.

      2. Click the Servers tab to view the servers where the disk has been attached.
      3. Click to select servers and click Detach Disk.

        Shared EVS disks support batch detachment, so you can select multiple servers at a time.

        The Detach Disk dialog box is displayed.

      4. Click Yes to detach the disk.
    • If no, perform the following procedure:
      1. In the disk list, locate the row that contains the target disk and choose More > Detach in the Operation column.

        The Detach Disk dialog box is displayed.

      2. Click to select servers.

        Shared EVS disks support batch detachment, so you can select multiple servers at a time.

      3. Click Yes to detach the disk.

    In the disk list, the disk status is Detaching, indicating that the disk is being detached from the server.

    If a shared disk has been attached to multiple servers and you only detach it from some of the servers, the disk status will go back to In-use after the disk has been detached. The disk status changes to Available only after the disk has been detached from all the servers.

Helpful Links

Parent Topic: Detaching and Deleting an EVS Disk