If you want to use data stored on an existing or a released disk to perform data extraction or fault analysis, you can use a snapshot of the disk to create disks. You can create disks from snapshots of system disks or data disks.

Prerequisites

A snapshot is created from a system disk or data disk. The snapshot ID is obtained. For more information, see Create a snapshot of a disk.

Background information

When you create a disk from a snapshot, take note of the following items:
  • Disks are independent of each other and cannot be merged by formatting. Therefore, we recommend that you determine the number and capacity of disks that you need before you create them.
  • We recommend that you do not use Logical Volume Manager (LVM) to create logical volumes on multiple disks. This is because a snapshot can back up the data only of a single disk. If you create a logical volume on multiple disks by using LVM, data discrepancies may occur when you roll back these disks.
  • If you want to attach the new disk to the Elastic Compute Service (ECS) instance to which the disk from which the snapshot was created was attached, you must change the UUID of the new disk. For more information, see Modify the UUID of a disk.
  • You can use a snapshot to create disks across zones.

Procedure

  1. Log on to the ECS console.
  2. In the left-side navigation pane, choose Storage & Snapshots > Disks.
  3. On the Disks page, click Create Disk.
  4. On the Disk page, click Create from Snapshot and select the snapshot from which you want to create disks.
    Create a disk from a snapshot
  5. Configure other parameters described in the following table for the disks.
    Parameter Description
    Attach Specify whether to attach the created disks to ECS instances.
    • Not Attach: creates disks without attaching them to ECS instances.

      If you select this option, only pay-as-you-go disks can be created. The disks and the ECS instances to which you want to attach the disks must reside within the same zone. The region and zone of a disk cannot be changed after the disk is created. Proceed with caution when you specify Region.

    • Attach to ECS Instance: creates disks and attaches the disks to the specified ECS instance.

      If you select this option, you must specify ECS Instance by selecting a destination region and an ECS instance.

    Note You can use a snapshot to create disks across zones.
    Billing Method Specify the billing method of the disks.
    • Pay-As-You-Go: Pay-as-you-go disks can be attached to subscription or pay-as-you-go instances.
    • Subscription: Subscription disks must be attached to subscription instances.
    Storage Select a disk category and specify the disk capacity.
    You must specify a disk capacity of at least the same size as the snapshot. If the disk capacity that you specify is greater than the snapshot size, you must re-partition the disk to ensure that the excessive disk capacity can be used.
    Notice If the snapshot is less than 2,048 GiB in size and you want to specify a disk capacity of greater than 2,048 GiB, make sure that the source disk of the snapshot uses the GUID Partition Table (GPT) partition format. If the source disk does not use GPT, we recommend that you specify a disk capacity of less than 2,048 GiB to prevent data loss during partitioning. For more information, see Partition and format a data disk larger than 2 TiB in size

    The following section describes other parameters:

    • Performance Level: You can set performance levels only for enhanced SSDs (ESSDs). You can select a performance level based on the capacity of an ESSD. The disk performance varies with the capacity of the ESSD and the performance level. For more information, see ESSDs.
    • Disk Encryption: Disk encryption is suitable for scenarios that require data security and regulatory compliance. If you select this option, data stored on the created disks is automatically encrypted.
    Quantity Specify the number of disks that you want to create.
    Note
    • When you create disks, take note of the number of data disks on the instance to which you want to attach the disks.Up to 16 data disks can be attached to a single instance. For more information, see the "Elastic Block Storage (EBS) limits" section in Limits.
    • Pay-as-you-go disks have capacity quotas. The total capacity that you purchase cannot exceed your capacity quota balance. You can use the following formula to calculate the total disk capacity: Total capacity = Capacity of a single disk × Number of disks. After you configure the disk category, the purchased capacity and the capacity quota balance are displayed on the disk buy page.
    Release Specify whether to release the automatic snapshots of the disks along with them or release the disks along with the instance to which they are attached. This parameter is available only when you select Attach to ECS Instance and set Billing Method to Pay-as-you-go.
    Terms of Service Read and select ECS Terms of Service.
    Others (Optional) Specify the Disk Name, Description, Tags, and Resource Group parameters for easy management.
  6. Confirm the configurations and fees and click Preview.
  7. In the Preview message, confirm the purchase information and click Create.
    After the disks are created, you can view the created disks on the Disks page. However, these disks cannot be directly used on ECS instances. You must perform the following operations before you can use the disks on ECS instances.

What to do next

The following table describes the operations that you must perform before you can use the created disks.
Scenario What to do next
You select Attach to ECS Instance when you create the disks
  • Windows: No operations are required.
  • Linux: Log on to the instance and run the mount command: 
    mount <Disk partition> <Mount point>
    Notice If you want to attach a new disk to the ECS instance to which the disk from which the snapshot was created was attached, you must change the UUID of the new disk before you can attach it to the ECS instance. For more information, see Modify the UUID of a disk.
You select Not Attach when you create the disks
  • Windows: Attach a data disk.
  • Linux:
    1. Attach a data disk
    2. Log on to the instance and run the mount command: 
      mount <Disk partition> <Mount point>
    Notice If you want to attach a new disk to the ECS instance to which the disk from which the snapshot was created was attached, you must change the UUID of the new disk before you can attach it to the ECS instance. For more information, see Modify the UUID of a disk.