Purchasing an EVS Disk

Scenarios

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.

Constraints

**Table 1** 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, the 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 be used as a data disk only. 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 the servers, the disks will have the same billing mode as their servers.
Separately purchased yearly/monthly disks that attached to a cloud server later cannot be renewed or unsubscribed from together with the server. Such disks may expire earlier than the server, and if this happens, service 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

Sign in to the EVS console.
Click in the upper left corner and select a region.
In the upper right corner, click Buy Disk.

Configure disk parameters according to Table 2.

**Table 2** Parameter description
Parameter	Example Value	Description
Billing Mode	Pay-per-use	You can pay for EVS disks in two ways: Yearly/Monthly Pay-per-use
Region	-	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.
AZ	AZ1	The availability zone (AZ) where you want to create the disk.
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.
Data Source (Optional) Create from backup Create from snapshot Create from image	Create from backup: autobackup-001	Optional Create from backup: The backup data is used to create the disk. Click Create from and choose Backup. On the displayed page, select the target backup and click OK. Create from snapshot: The snapshot data is used to create the disk. Click Create from and choose Snapshot. On the displayed page, select the target snapshot and click OK. NOTE: For details about how to create disks from snapshots, see Creating a Disk from a Snapshot. Create from image: The image data is used to create the disk. Click Create from and choose Image. On the displayed page, select the target 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.
Disk Capacity (GiB)	100 GiB	The 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.
More > Advanced Settings Share SCSI Encryption	-	Optional 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. Encryption This option is only used to encrypt data disks, and you need to create an agency to grant KMS access permissions to EVS. After the access permissions are granted, 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 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. Keys can only be shared with accounts, not users. NOTE: System disk encryption depends on images. For details, see Encrypting Images. 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.
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, which means 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.

Click Next.
- If you select Yearly/Monthly for Billing Mode:
  1. Check the disk details on the confirmation page.
  2. Confirm the information and click Submit.
  3. On the Pay page, select a desired payment method and confirm the payment. The system displays a message indicating payment processed successfully.
  4. Click Back to Elastic Volume Service to return to the Elastic Volume Service page.
- If you select Pay-per-use for Billing Mode:
  1. Check the disk details on the confirmation page.
  2. Confirm the information and click Submit. The system displays a message indicating request submitted successfully.
  3. Click Go to Disk List to return to the Elastic Volume Service page.
In the disk list, view the disk status.

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