# Create an EVS Disk

#### Scenarios

EVS disks can be used as system disks or data disks for servers.

- When a server is created, a system disk is automatically created and attached. You cannot create a system disk separately. The maximum size of a system disk is 1024 GB.
- Data disks can be created during or after the server creation. If you create data disks during the server creation, the system will automatically attach the data disks to the server. If you create data disks after the server creation, you need to manually attach the data disks. The maximum size of a data disk is 32768 GB.

This section describes how to separately create disks on the EVS console.

#### Procedure

1. Log in to the management console.
2. Click in the upper left corner and select the desired region and project.
3. Under Storage, click Elastic Volume Service.

   The disk list page is displayed.

4. Click Create Disk.

   - Figure 1 shows the parameter setting of non-encrypted disks.
     Figure 1 Non-encrypted disks
   - Figure 2 shows the parameter setting of encrypted disks.
     Figure 2 Encrypted disks
5. Configure basic disk information according to Table 1.

   Table 1 Parameter description
   Parameter | Description | Example Value
   --- | --- | ---
   Region | Mandatory Resources are region-specific and cannot be used across regions through internal network connections. For low network latency and quick resource access, select the nearest region. | eu-de

   AZ

   Mandatory

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

   NOTE:
   - Disks can only be attached to the servers in the same AZ.
   - The AZ of a disk cannot be changed after the disk has been created.

   eu-de-1

   Disk Type

   Mandatory
   - Common I/O
   - High I/O
   - Ultra-high I/O
   - High I/O (Performance optimized I)
   - Ultra-high I/O (Latency optimized)
   NOTE:
   - When disks are created from backups:

     If the disk type of the backup's source disk is common I/O, high I/O, or ultra-high I/O, you can create disks of any of these types.

     If the disk type of the backup's source disk is high I/O (performance optimized I) or ultra-high I/O (latency optimized), you can create disks of any of the two types.

   - When a disk is created from a snapshot, the disk type of the newly created disk will be consistent with that of the snapshot's source disk.
   - For details about disk types, see Disk Types and Performance.

   Common I/O

   Capacity (GB)

   Mandatory

   Specifies the disk size. Only data disks can be created on the current page, and the disk capacity ranges from 10 GB to 32768 GB.

   NOTE:
   - When you use a backup to create a disk, the disk capacity must be greater than or equal to the backup size. In the condition that you do not specify the disk capacity, if the backup size is smaller than 10 GB, the default capacity 10 GB will be used as the disk capacity; if the backup size is greater than 10 GB, the disk capacity will be consistent with the backup size.
   - When you use a snapshot to create a disk, the disk capacity must be greater than or equal to the snapshot size. In the condition that you do not specify the disk capacity, if the snapshot size is smaller than 10 GB, the default capacity 10 GB will be used as the disk capacity; if the snapshot size is greater than 10 GB, the disk capacity will be consistent with the snapshot size.

   20 GB

   Create from backup

   Optional

   Specifies to create the disk from a backup.

   Click Select Data Source and choose Create from backup. On the displayed page, select the target backup and click OK.

   NOTE:
   - You can select a backup created by the current tenant or shared with the current tenant by another tenant.
   - 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 be used to create another disk only after disk A has been created.
   - If a disk is created from a backup of a system disk, the new disk can be used as a data disk only.

   autobackup-001

   Create from snapshot

   Optional

   Specifies to create the disk from a snapshot.

   Click Select Data Source and choose Create from snapshot. On the displayed page, select the target snapshot and click OK.

   NOTE:
   - The disk type of the new disk is the same as that of the snapshot's source disk.
   - The device type of the new disk is the same as that of the snapshot's source disk.
   - The encryption attribute of the new disk is the same as that of the snapshot's source disk.

   For details about the disk creation from snapshots, see Creating an EVS Disk from a Snapshot.

   snapshot-001

   Auto Backup

   Optional

   If auto backup is enabled, the system automatically creates backups for the disk data at specified time points and deletes outdated backups according to the configured backup policy.

   When Enable is selected, a backup policy must be configured. You can either use the default backup policy or customize the policy based on your service requirements.

   NOTE:

   For details about the backup policy, see Managing EVS Backup.

   -

   Share

   Optional
   - If Share is not selected, a common disk is created.
   - If Share is selected, a shared disk is created, and the shared disk can be attached to multiple servers.

   If both SCSI and Share are selected, a shared SCSI disk is created.

   NOTE:

   The sharing attribute of a disk cannot be changed after the disk has been created.

   For details about shared EVS disks, see Managing a Shared EVS Disk.

   -

   SCSI

   Optional
   - If SCSI is not selected, a VBD disk is created. VBD is the default device type of EVS disks.
   - If SCSI is selected, a SCSI disk is created. Such disks allow the server OS to directly access the underlying storage media and send SCSI commands to the disks.
   NOTE:

   The device type of a disk cannot be changed after the disk has been created.

   For details about the ECS types, OSs, and ECS software supported by SCSI EVS disks, see Device Types and Usage Instructions.

   -

   Encryption

   Optional

   Disk encryption is used for data disk encryption only. For system disk encryption, see the Image Management Service User Guide.

   To use the disk encryption function, select Encryption. The displayed dialog box contains the following parameters:
   - Create Agency

     An agency is a trust relationship between two tenants or services. A tenant can create an agency to grant resource access rights to another tenant or service. If the KMS access rights are not granted to EVS, the Create Agency dialog box will be displayed. Otherwise, it will not be displayed.

     Click Yes to grant the KMS access rights to EVS. After the rights have been granted, EVS can obtain KMS keys to encrypt or decrypt EVS disks.

     After the KMS access rights have been granted, follow-up operations do not require the rights to be granted again.

   - KMS Key Name
     NOTE:

     KMS Key Name is displayed only after the KMS access rights have been granted. For details, see "Create Agency" above.

     KMS Key Name is the identifier of the key, and you can use KMS Key Name to specify the KMS key that is to be used for encryption. One of the following keys can be used:
     - Default Master Key: After the KMS access rights have been granted to EVS, the system automatically creates a Default Master Key and names it evs/default.
     - CMKs: Existing or newly created CMKs. For details, see Management > Creating a CMK in the Key Management Service User Guide.
   NOTE:
   - Before you use the EVS disk encryption function, KMS access rights need to be granted to EVS. If you have the right to grant the permission, grant the KMS access rights to EVS directly. If you do not have this permission, contact a user with the security administrator rights to grant KMS access rights to EVS, then repeat the preceding operations.
   - The encryption attribute of a disk cannot be changed after the disk has been created.

   For details, see EVS Disk Encryption.

   -

   Tag

   Optional

   During the EVS disk creation, you can tag the EVS resources. Tags identify cloud resources for purposes of easy categorization and quick search.

   A tag is composed of a key-value pair.
   - Key: Mandatory if the disk is going to be tagged
     - Must be unique for each resource.
     - Can contain a maximum of 36 characters.
     - Can contain only digits, letters, hyphens (-), and underscores (_).
   - Value: Optional if the disk is going to be tagged
     - Can contain a maximum of 43 characters.
     - Can contain only digits, letters, hyphens (-), and underscores (_).
   NOTE:
   - A maximum of 10 tags can be added for an EVS disk.
   - Tag keys of the same EVS disk must be unique.
   - Except for tagging the disk during disk creation, you can also add, modify, or delete tags for existing disks. For details, see Managing a Tag.

   For details about tags, see the Tag Management Service User Guide.

   -

   Disk Name

   Mandatory
   - If you create disks individually, this parameter value is used as the actual disk name.

     The name can contain a maximum of 64 characters.

   - If you create disks in a batch, this parameter value is used as the prefix of disk names, and one disk name will be composed of this parameter value and a four-digit number.

     The name can contain a maximum of 59 characters.

   For example, if you create two disks and set volume for Disk Name, the EVS disk names will be volume-0001 and volume-0002.

   Quantity

   Optional

   Specifies the number of disks to be created. The default value is set to 1, which means only one disk is created. Currently, you can create up to 100 disks at a time.

   NOTE:
   - If the disk is created from a backup, batch creation is not possible, and this parameter must be set to 1.
   - If the disk is created from a snapshot, batch creation is not possible, and this parameter must be set to 1.

   1

6. Click Create Now.
7. On the Details page, check the disk details.

   - If you do not need to modify the specifications, click Submit to start the creation.
   - If you need to modify the specifications, click Previous to modify parameters.
8. Go back to the disk list page and view the disk status.

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

Parent topic: Getting Started