Creating an Encrypted EVS Disk

EVS enables you to encrypt data on newly created disks as required.

Disk Encryption Scenarios

System disk encryption

System disks are purchased along with servers and cannot be purchased separately. So, whether a system disk is encrypted or not depends on the image you select when creating the server.

**Table 1** Relationship between images and system disk encryption
Whether to Encrypt System Disk When Purchasing Server	Whether to Create Server from an Encrypted Image	Whether System Disk Will Be Encrypted	Description
Yes (key A)	Yes (key B)	Yes (key A)	To encrypt system disks, see Purchasing an ECS in Custom Config Mode. For details about how to encrypt images, see Encrypting Images.
Yes (key A)	No	Yes (key A)
No	Yes (key B)	Yes (key B)
No	No	Default encryption disabled Default encryption enabled	Default encryption disabled: If you want to use a non-encrypted image to create an encrypted system disk, replicate the image as an encrypted image and then use it to create a server. For details, see Replicating Images Within a Region. Default encryption enabled: You can use the key preset for default encryption or change the key as required.

Data disk encryption

Data disks can be purchased along with servers or separately. Whether data disks are encrypted or not depends on their data sources. See the following table for details.

**Table 2** Relationship between backups, snapshots, images, and data disk encryption
Creation Scenario	Whether Data Source Is Encrypted	Whether Data Disk Will Be Encrypted	Description
No data source selected	Empty disk	Encrypted/Not encrypted	When you create a disk on the EVS console or together with an ECS, you can choose whether to encrypt the disk or not. Once the disk is created, its encryption attribute cannot be changed.
Creating from a backup	Any	Encrypted/Not encrypted	When you create a disk from a backup, you can choose whether to encrypt the disk or not. The disk's encryption attribute does not need to be the same as the backup. When you create a backup for a system or data disk, the backup inherits the disk's encryption attribute.
Creating from an image	Encrypted	Encrypted	The disk inherits the source disk's encryption attribute.
Creating from an image	Not encrypted	Not encrypted	The disk inherits the source disk's encryption attribute.
Creating from a legacy snapshot	Not encrypted	Not encrypted	The disk inherits the source disk's encryption attribute.
Creating from a legacy snapshot	Encrypted	Encrypted	The disk inherits the source disk's encryption attribute.
Creating from a standard snapshot (Instant Snapshot Restore is enabled, but data upload is not complete)	Not encrypted	Not encrypted	The disk inherits the source disk's encryption attribute.
	Encrypted	Encrypted	The disk inherits the source disk's encryption attribute.
Creating from a standard snapshot (data upload is complete)	Any	Encrypted/Not encrypted	The disk's encryption attribute does not need to be the same as the source disk.

Constraints

**Table 3** Constraints on disk encryption
Item	Description
Disk types supporting encryption	All disk types support encryption, but the encryption attribute of an existing disk cannot be changed.
Disk encryption	The encryption attribute of a disk cannot be changed after the disk is created, meaning that: An encrypted disk cannot be changed to a non-encrypted disk. A non-encrypted disk cannot be changed to an encrypted disk.
User permissions	When a user uses encryption, the condition varies depending on whether the user is the first one ever in the current region or project to use this function. If the user is the first user, the user needs to follow the prompt to create an agency, which grants EVS KMSAccess permissions to EVS. Then, the user can create and obtain keys to encrypt and decrypt disks. If the user is not the first user, the user can use encryption directly.
Image encryption	Encrypted images cannot be replicated across regions. Encrypted images cannot be changed to non-encrypted images. Encrypted images cannot be exported.

Billing

If KMS encryption is used, what you use beyond the free quota given by KMS will be billed. For details, see DEW Billing.

Creating an Encrypted EVS Disk

Before you use the encryption function, KMS access permissions need to be granted to EVS. If you have the Security Administrator permissions, grant the KMS access rights to EVS directly. If you do not have this permission, contact a user with the Security Administrator permissions to grant KMS access rights to EVS and then select the encryption option to create an encrypted disk.

For details about how to create an encrypted disk, see Purchasing an EVS Disk.

You can use encrypted system disks immediately after they are created. You need to attach and initialize encrypted data disks after they are created.

**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.

Detaching an Encrypted EVS Disk

Before you detach a disk encrypted by a custom key, check whether the custom key is disabled or scheduled for deletion.

If the custom key is available, the disk can be detached and re-attached, and data on the disk will not be lost.
If the custom key is unavailable, the disk can still be used, but there is no guarantee for how long it will be usable. If the disk is detached, it will be impossible to re-attach it later. In this case, do not detach the disk without a working custom key.

The restoration method varies depending on the CMK status. For details, see Keys Used for EVS Encryption.

For details about how to detach an encrypted disk, see Detaching an EVS Disk.