Help Center/ Elastic Volume Service/ User Guide/ Purchasing and Using an EVS Disk/ Purchasing an EVS Disk
Updated on 2026-02-13 GMT+08:00
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Purchasing an EVS Disk

Scenarios

You can use EVS disks as system disks or data disks for servers. If the storage space on your servers is insufficient, you can buy EVS disks to add more storage space. This section describes how to buy new EVS disks.

Table 1 Scenarios

Buy On

Description

Reference

EVS console

You can only buy data disks on the EVS console. You can select to attach the disk to an ECS during the purchase or manually attach it after the purchase.

Buying Disks On the EVS Console

Cloud server console
  • The system automatically attaches the data disks purchased together with servers or those added after the server purchase.
  • You can only buy system disks together with servers. After that, the system automatically attaches the system disks.

Purchasing and Using a Linux ECS

Constraints

Table 2 Constraints

Category

Description

General constraints
  • Capacities of multiple disks cannot be combined, and the capacity of a single disk cannot be split.
  • You can only attach disks to servers in the same region and AZ. Once a disk is created, its region and AZ cannot be changed.
  • There are quantity and capacity quotas on EVS disks, so properly plan the number of disks and total disk capacity your workloads require. For details, see Managing EVS Quotas.
  • After a disk is created, its device type, sharing attribute, and encryption attribute cannot be changed.
  • You can create a maximum of 100 disks in a batch.

Create from backup
  • One backup cannot be used for concurrent disk creation operations at the same time. For example, if you are creating disk A from a backup, this backup can only be used to create another disk after disk A has been created.
  • If a disk is created from a backup of a system disk, the new disk can only be used as a data disk.
  • When you create a disk from a backup, the disk capacity must be greater than or equal to the backup size. In the condition that you do not specify a disk capacity, if the backup size is smaller than 10 GiB, the default capacity 10 GiB will be used as the disk capacity; if the backup size is greater than 10 GiB, the backup size will be used as the disk capacity.

Create from image
  • The device type of the new disk is the same as that of the image's source disk.
  • The encryption attribute of the new disk is the same as that of the image's source disk.

Create from snapshot

When you create a disk from a snapshot, the disk capacity must be greater than or equal to the snapshot size. In the condition that you do not specify a disk capacity, if the snapshot size is smaller than 10 GiB, the default capacity 10 GiB will be used as the disk capacity; if the snapshot size is greater than 10 GiB, the snapshot size will be used as the disk capacity.

Billing

  • EVS disks are billed based on the disk type, capacity, and usage duration. For details, see Billing for EVS Disks.
  • If you create disks together with a server, the disks will have the same billing mode as their server.
  • Yearly/Monthly disks that you add to a cloud server after the server purchase have a different expiration time as the server. Such disks cannot be automatically renewed or unsubscribed from together with the server. If they expire earlier, services on the server may be interrupted.
  • If KMS encryption is used, what you use beyond the free quota given by KMS will be billed. For details, see DEW Billing.

Video Tutorial

Buying Disks On the EVS Console

  1. Sign in to the EVS console.
  2. Click in the upper left corner and select a region.
  3. In the upper right corner, click Buy Disk.
  4. Configure disk parameters according to Table 3.

    Table 3 Parameter description

    Parameter

    Example Value

    Description

    Attach to Server

    Now
    • Now: If you select this option, you need to select a server to attach the disk. The billing mode of the disk will be the same as the selected server.
    • Later: When no server is available, you can select this option to create the disk first and attach the disk after the purchase.
    NOTE:

    This parameter is available only in some regions. Whether it is displayed depends on the region where you use EVS.

    Region

    -

    Resources in different regions cannot communicate with each other over an internal network. For low network latency and quick resource access, select the nearest region.

    AZ

    AZ1

    The availability zone (AZ) where you want to create the disk.

    Billing Mode

    Pay-per-use

    You can pay for EVS disks in two ways:

    • Yearly/Monthly
    • Pay-per-use
    NOTICE:
    • Selecting Now for Attach to Server:
      • If you select a yearly/monthly server, only yearly/monthly billing is available for the disk. If you want to buy a pay-per-use disk for the yearly/monthly server, select Later for Attach to Server, buy a pay-per-use disk, and attach it to the yearly/monthly server after the purchase.
      • If you select a pay-per-use server, only pay-per-use billing is available for the disk. If you want to buy a yearly/monthly disk for the pay-per-use server, select Later for Attach to Server, buy a yearly/monthly disk, and attach it to the pay-per-use server after the purchase.
    • Selecting Later for Attach to Server: If you buy a yearly/monthly disk and attach it after the purchase, the disk cannot be renewed or unsubscribed from together with its server and may have an expiration time different from the server.

    Data Source

    -

    Optional

    Supported data source types include backup, snapshot, and image.

    • Backup: The disk will be created from a backup.

      Choose Backup > Select Data Source. On the displayed page, select a backup and click OK.

    • Snapshot: The disk will be created from a snapshot.

      Choose Snapshot > Select Data Source. On the displayed page, select a snapshot and click OK.

      NOTE:

      For more information about creating disks from snapshots, see Creating a Disk from a Snapshot.

    • Image: The disk will be created from an image.

      Choose Image > Select Data Source. On the displayed page, select an image and click OK.

    Disk Type

    Ultra-high I/O

    EVS disk types vary depending on regions. See the EVS types displayed on the console.

    To learn more about disk types, see Disk Types and Performance.

    NOTE:

    General Purpose SSD V2 disks allow you to specify the disk IOPS and throughput.

    You can change the disk type after a disk is created. For details, see Changing the EVS Disk Type (OBT).

    Capacity (GiB)

    100 GiB

    Set a disk capacity. You can only create data disks on the current page. The disk capacity ranges from 10 GiB to 32,768 GiB.

    NOTE:

    The system shows you the remaining disk space you can purchase. If the disk capacity you need exceeds the upper limit, click Increase Quota to obtain a higher quota. You can purchase the disk capacity you need after the request is approved.

    Disk Encryption

    -

    You can only encrypt data disks here, and you need to create an agency to authorize EVS to access KMS. After the authorization is successful, configure the following parameters on the Encryption Setting page displayed:

    • Select an existing key

      If you select Select an existing key, select a key from the drop-down list. You can select one of the following keys:

      Default keys: After KMS access permissions are granted to EVS, the system automatically creates a default key and names it evs/default.

      Custom keys: You can choose an existing key or create a new one. For details about how to create a key, see Creating a Custom Key.

    • Enter a key ID

      If you select Enter a key ID, enter an ID of a key shared with you by another account. Ensure that the shared key is in the same region where you want to create the disk. For how to share keys, see Creating a Grant for a Custom Key. Keys can only be shared with accounts, not users.

    NOTE:
    • Before using encryption, you need to create an agency to grant KMS access permissions to EVS. If you have the right to grant the permission, grant KMS access permissions to EVS directly. After KMS access permissions are granted, follow-up operations do not require the permissions to be granted again. If you do not have this permission, contact a user with the security administrator permissions to grant KMS access permissions to EVS, then repeat the preceding operations.

    Advanced Settings

    • Share
    • SCSI

    -
    • Share

      If you select Share, a shared disk will be created. A shared disk can be attached to up to 16 servers. If you do not select Share, a non-shared disk will be created, and the disk can be attached to one server only.

      If you select both Share and SCSI, a shared SCSI disk will be created.

      NOTE:

      For details about shared EVS disks, see Managing Shared EVS Disks.

    • SCSI

      If you select SCSI, a SCSI disk will be created. Such disks allow the server OS to directly access the underlying storage media and send SCSI commands to the disks. If you do not select SCSI, a VBD disk will be created. That said, the disk device type is VBD, the default device type.

      NOTE:

      To learn more about the ECS types and OSs supported by SCSI disks and the requirements on the ECS software, see Device Types.

    Automatic Backup

    -

    Optional

    CBR lets you back up EVS disks and ECSs and use the backups to restore data. After you configure automatic backup, the system will associate the EVS disk with a backup vault and apply the selected policy to the vault to periodically back up the disk.

    • Skip this configuration if backup is not required. If you need backup protection after a disk has been purchased, go to the CBR console, locate the desired vault, and associate the disk with the vault.
    • Use existing:
      1. Vault: Select an existing vault from the drop-down list.
      2. Backup Policy: Select a backup policy from the drop-down list, or go to the CBR console and configure a desired one.
    • Buy new:
      1. Enter a vault name, which can contain a maximum of 64 characters, including letters, digits, underscores (_), and hyphens (-), for example, vault-f61e. The default naming rule is vault_xxxx.
      2. Enter a vault capacity for storing disk backups. The vault capacity cannot be less than the size of the disk to be backed up. The value ranges from the disk size to 10,485,760 in the unit of GiB.
      3. Select a backup policy from the drop-down list, or go to the CBR console and configure a desired one.

    Disk Name

    Assume that you create two disks and enter volume for Disk Name, the EVS disk names will be volume-0001 and volume-0002.

    • If you create a single disk, the name you entered will be used as the disk name.

      The value can contain a maximum of 64 characters.

    • If you create multiple disks in a batch, the name you entered will be used as the prefix of disk names. Each disk name will be composed of the name you entered and a four-digit number.

      The value can contain a maximum of 59 characters.

    Tag

    -

    Optional

    You can add tags when creating disks. Tags can help you identify, classify, and search for your disks. For details about tag rules, see Adding a Tag.
    NOTE:
    • Tag rules vary depending on regions. See the rules displayed on the console.
    • Except for tagging the disk during disk creation, you can also add, modify, or delete tags for existing disks. For more information about tags, see Managing EVS Tags.

    Enterprise Project

    default

    When creating EVS disks, you can add the disks to an existing enterprise project.

    An enterprise project facilitates project-level management and grouping of cloud resources and users. The default project is default.

    Quantity

    Usage Duration: 1 year

    Select Auto-renew.

    Quantity: 1
    • Usage Duration: This parameter is mandatory if you select Yearly/Monthly for Billing Mode.

      You can choose from 1 month to 3 years.

    • Auto-renew: This parameter is optional.

      Your order will automatically renew on a monthly or yearly basis, depending on if you purchased by month or by year.

    • Quantity: This parameter is optional.

      The preset disk quantity is 1. It means that only one disk will be created. You can create a maximum of 100 disks at a time.

    NOTE:

    The system shows you the remaining number of disks you can purchase. If the number of disks you need exceeds the upper limit, click Increase Quota to obtain a higher quota. You can purchase the disks you need after the request is approved.

  5. Check your configurations on the configuration summary page. If the information is correct, click Submit.

    • If you select Yearly/Monthly for Billing Mode:
      1. On the displayed page, select a desired payment method and confirm the payment. The system displays a message indicating payment processed successfully.
      2. Click Go to Elastic Volume Service Console to return to the Elastic Volume Service page.
    • If you select Pay-per-use for Billing Mode:

      On the page with message "Task submitted successfully" displayed, click Go to Disk List to return to the Elastic Volume Service page.

  6. In the disk list, view the disk status.

    When the disk status changes to Available, the disk is successfully created.

  7. Perform follow-up operations. After new disks are purchased, attach and initialize them based on different scenarios.

    Table 4 Follow-up operations

    Step

    Description

    Step 1: Attach the disk.

    If you choose not to attach the disk when purchasing the disk, you need to manually attach it later.

    Step 2: Initialize the disk.

    The procedure for initializing a newly created empty data disk differs from that for a data disk with data on it. For details, see Initialization Overview.

Related Links

Parent Topic: Purchasing and Using an EVS Disk