Basic Concepts

Images are classified as public, private, and shared.

Image Type	Description
Public	A public image is a standard, widely used image. It contains an OS and preinstalled public applications and is available to all users. Public images are very stable and their OS and any included software have been officially authorized for use. If a public image does not contain the environments or software you need, you can use a public image to create an ECS and then deploy the required environments or software on it.
Private	A private image contains an OS or service data, preinstalled public applications, and a user's personal applications. Private images are only available to the users who created them. A private image can be a system disk image, data disk image, ISO image, or full-ECS image. A system disk image contains an OS and preinstalled software for various services. You can use a system disk image to create ECSs and migrate your services to the cloud. A data disk image contains only service data. You can use a data disk image to create EVS disks and use them to migrate your service data to the cloud. An ISO image is created from an external ISO image file. It is a special image that is not available on the ECS console. A full-ECS image contains an OS, preinstalled software, and service data. A full-ECS image is created using differential backups and the creation takes less time than creating a system or data disk image that has the same disk capacity.
Shared	A shared image is a private image another user has shared with you. For more information, see "Sharing Images" in Image Management Service User Guide.

Image Type

Description

Public

A public image is a standard, widely used image. It contains an OS and preinstalled public applications and is available to all users. Public images are very stable and their OS and any included software have been officially authorized for use. If a public image does not contain the environments or software you need, you can use a public image to create an ECS and then deploy the required environments or software on it.

Private

A private image contains an OS or service data, preinstalled public applications, and a user's personal applications. Private images are only available to the users who created them.

A private image can be a system disk image, data disk image, ISO image, or full-ECS image.

A system disk image contains an OS and preinstalled software for various services. You can use a system disk image to create ECSs and migrate your services to the cloud.
A data disk image contains only service data. You can use a data disk image to create EVS disks and use them to migrate your service data to the cloud.
An ISO image is created from an external ISO image file. It is a special image that is not available on the ECS console.
A full-ECS image contains an OS, preinstalled software, and service data. A full-ECS image is created using differential backups and the creation takes less time than creating a system or data disk image that has the same disk capacity.

Shared

A shared image is a private image another user has shared with you.

For more information, see "Sharing Images" in Image Management Service User Guide.

You can modify an image, share images, export images, encrypt images, replicate images, export an image list, and delete images.

**Table 1** Managing private images
Feature	Description	Helpful Link
Modifying an image	You can modify the following attributes of an image: name, description, minimum memory, maximum memory, and advanced functions such as NIC multi-queue and SR-IOV driver.	Modifying an Image
Sharing images	You can share an image with other accounts. These accounts can use your shared private image to quickly create ECSs or EVS disks.	Sharing Images Image Sharing
Exporting images	You can export private images to your OBS bucket and download them to your local PC for backup.	Exporting an Image Image Export
Encrypting images	You can create encrypted images to improve data security. KMS envelope encryption is used. Encrypted images can be created from external image files or encrypted ECSs.	Encrypting Images
Replicating images	By replicating images, you can convert encrypted and unencrypted images into each other or enable some advanced features, for example, fast instance provisioning.	Replicating Images Within a Region
Tagging an image	You can tag your private images for easy management and search.	Managing Tags
Exporting image list	You can export the public or private image list in a given region as a CSV file for local maintenance and query.	Exporting Image List
Deleting images	You can delete images that will be no longer used. Deleting an image does not affect the ECSs created from that image.	Deleting Images