Elastic Compute Service:Attach a data disk

Limits

Procedure

This section describes how to attach a data disk to an ECS instance on the instance details page.

1. Log on to the ECS console.

2. In the left-side navigation pane, choose Instances & Images > Instances.

3. In the top navigation bar, select the region and resource group to which the resource belongs.

4. Find the instance to which you want to attach a disk and click the instance ID.

5. Click the Block Storage tab. Above the disk list, click Attach Cloud Disk .

   

6. Attach the disk to the destination instance and select a release mode.

   Parameter	Description
   Disk	Select a disk that you want to attach to the ECS instance.
   Release Cloud Disk with Instance	Select this option if you want to release the disk when the ECS instance is released. Clear this option if you want to retain the disk when the ECS instance is released. Important If a system disk was detached from another instance and attached as data disk to the instance that you select, the Release Disk with Instance feature takes effect on the source ECS instance from which the system disk is detached, not on the current instance.
   Delete Automatic Snapshots While Releasing Disk	Select this option if you want to delete the automatic snapshots created from the disk when the disk is released. Important We recommend that you clear this option to retain backup data on the disk.

7. Click Next.

8. In the Attach Cloud Disk dialog box, click Initialize Now in the Initialization Method section. Follow the on-screen instructions to initialize the disk or to mount a file system on the disk by using Cloud Assistant or referring to the relevant documentation.

   Why cannot Cloud Assistant be used to initialize a disk?

   Cloud Assistant can only initialize a disk if the following conditions are met:

   • The multi-attach feature is disabled on the disk that you want to initialize. For more information, see Multi-attach for cloud disks.

   • The disk is attached to a Linux ECS instance, not a Windows instance.

   • The ECS instance is in the Running state, and Cloud Assistant Agent is installed on the instance. For more information, see Install Cloud Assistant Agent.

   • The disk is not a detached system disk.

   • A partition that you want to create on the disk is a GUID Partition Table (GPT) partition, and the file system type is Extended File System 4 (Ext4).

   • For newly created empty data disks that have no partitions or file systems, you must create partitions and file systems and then mount these file systems.

   • For disks created from snapshots or data disks detached from other instances that have no mounted file systems, you only need to mount the file systems. Mounting file systems dos not result in data loss.

   Create partitions and mount file systems

   Use Cloud Assistant on a Linux instance

   

   1. Specify the partition size and mount point.

      Note

      You can click Create Partition to add multiple partitions to the disk based on your business requirements. Up to five partitions can be added to each disk.

      • Partition size: The size of a single partition and the total size of all partitions cannot exceed the total capacity of the disk.

        Note

        1 MiB or 2 MiB of storage space must be reserved for the partition table and sector alignment. The partitioning feature automatically reduces the size of the last partition to reserve space. Therefore, the actual size of the partitions may be slightly less than specified size, and the total available capacity may be slightly less than the total capacity of the disk.

      • File system type: Only Ext4 file systems are supported. The default partition style is GPT.

      • Mount point: The mount point must start with a forward slash (/) and can contain letters and digits. Example: /mnt. You can specify an existing directory that does not contain data or a new directory as a mount point. The mount point cannot be duplicated.

        Important

        If the destination directory contains data, mounting partitions to the directory overwrites system files in the directory, which may cause data loss and affect business operations.

   2. Confirm and select the risk statement and then click OK.

      Note

      If you accidentally close the page, you can use Cloud Assistant to create partitions and file systems again by referring to Initialize a data disk whose size does not exceed 2 TiB on a Linux instance.

      When Normal appears in the Current Status column in the initialization task list, the disk is initialized.

   3. (Optional) Configure the system to automatically mount the partitions on instance startup. For details, see Step 4: Configure the disk partition to automatically mount on instance startup.

   Refer to documentation (CLI)

   If you cannot use Cloud Assistant to initialize the disk, perform the following operations:

   • For Linux instances: Initialize a data disk whose size does not exceed 2 TiB on a Linux instance.

   • For Windows instances: Initialize a data disk on a Windows instance.

   Only mount file systems

   Use Cloud Assistant on a Linux instance

   1. In the Partition and Mount Settings section, enter a mount point in the Mount Point column and click Manually Mount to mount the file system.

      Note

      You can specify an existing directory that does not contain data or another directory as a mount point. The mount points cannot be duplicated.

      

      Note

      If you accidentally close the page, you can use Cloud Assistant to mount the file system again. For more information, see Initialize a data disk whose size does not exceed 2 TiB on a Linux instance.

   2. (Conditionally required) If a disk created from a snapshot is attached to the original ECS instance to which the source disk of the snapshot is attached, the UUID of the new disk conflicts with the UUID of the source disk. You must change the UUID of the new disk. For more information, see Change the UUID of a disk.

   3. (Conditionally required) If a disk created from a snapshot is larger than the source disk, you must resize the partitions and file systems before using the disk in the operating system.

      • For Linux instances, see Extend the partitions and file systems of disks on a Linux instance.

      • For Windows instances, see Extend the partitions and file systems of disks on a Windows instance.

   4. (Optional) Configure the disk partitions to automatically mount on instance startup. For details, see Step 4: Configure the disk partition to automatically mount on instance startup.

   Refer to documentation (CLI)

   If you cannot use Cloud Assistant to mount file systems, perform the following steps:

   1. (Conditionally required) If the cloud disk created from a snapshot is attached to the Linux ECS instance to which the source disk of the snapshot is attached, the UUID of the new cloud disk conflicts with the UUID of the source disk. You must change the UUID of the new cloud disk. For more information, see Change the UUID of a disk.

   2. Mount partitions to the cloud disk or bring the disk online.

      • Linux instance

        1. Connect to the ECS instance to which the cloud disk is attached and run the following command to mount a partition to the disk:

           sudo mount <Disk partition name> <Mount point>

           • <Disk partition name>: Specify the name of the partition. Run the sudo fdisk -lu command to query the partition name. Example: /dev/vdc.

           • <Mount point>: Specify an existing directory or run the sudo mkdir -p <New directory> command to create a new directory as the mount point. Example: sudo mkdir -p /data.

           Sample mount command: sudo mount /dev/vdc /data.

        2. Write the new partition information to the /etc/fstab file. This way, the partition is automatically mounted on system startup. For more information, see the Step 4: Configure the disk partition to automatically mount on instance startup section of the "Initialize a data disk whose size does not exceed 2 TiB on a Linux instance" topic.

      • Windows instance

        1. Connect to the ECS instance to which the cloud disk is attached, click the icon, and then select Disk Management.

        2. Find the cloud disk that you want to manage, right-click a blank area, and select Online.