Image

What is Image?

An image is a template file used to create a VM instance or volume. Images are categorized into system images and volume images.

A system image contains an OS for running services. You can use a system image to create VM instances. A system image can be of the ISO or Image type.
A volume image contains only service data. You can use a volume image to create volumes. A volume image can only be of the Image type.
Image-type images can be in the raw, qcow2, or vmdk format.
Images are stored on image storage. When an image is used to create a VM instance or volume, the image is downloaded to a primary storage and cached there.

Add an Image

On the main menu of ZStack Cloud, choose Resource Center > Resource Pool > Compute Configuration > Image. On the Image page, click Add Image. The Add Image page appears.

The following lists the two image addition scenarios:

Add a system image.
Add a volume image.

Add System Image

On the displayed page, set the following parameters:

Name: Enter a name for the image.
The name must be 1 to 128 characters in length and can contain Chinese characters, letters, digits, spaces, hyphens (-), underscores (_), periods (.), parenthesis (), colons (:), and plus signs (+) and cannot begin or end with spaces.
Description: Optional. Enter a description for the image.
Image Type: System Image.
Image Format: Select an image format. You can select qcow2, iso, raw, or vmdk.
Note: vmdk-formatted image files will be auto-converted to qcow2-formatted files if uploaded to an ImageStore image storage, and to raw-formatted files if uploaded to a Ceph image storage.
CPU Architecture: Select a CPU architecture for the image. VM instances created from the image use this CPU architecture.
Note: If you select aarch64 or mips64, set the BIOS mode to UEFI.
Platform: Select an image platform type.
The platform type of an image decides whether the VM instances created based on the image use KVM VirtIO drivers, including VirtIO disk drivers and VirtIO NIC drivers. The following lists the available platform types of an image:
- Linux: If VirtIO is enabled, the image operating system will attach VirtIO drivers, including a VirtIO disk driver and VirtIO NIC driver. If it is disabled, the image operating system will not attach VirtIO drivers, such as RHEL 5.8, and will use a QEMU device instead.
- Windows: If VirtIO is enabled, the image operating system will attach VirtIO drivers, including a VirtIO disk driver and VirtIO NIC driver. If it is disabled, the image operating system will not attach VirtIO drivers and use a QEMU device instaed.
- Other: If VirtIO us enabled, the image operating system will attach VirtIO drivers, including a VirtIO disk driver and VirtIO NIC driver. If it is disabled, the image operating system will use a QWMU device. Platforms of this type allows compatibility with earlier-version operationg systems that do not support VirtIO drivers.
OS: Select an operating system that is consistent with the image.
VirtIO: Choose whether to enable VirtIO according to your operating system and platform.
Image Storage: Select an image storage.
Image Path: Specify an image URL or upload a local file:
- URL: Enter a specified URL to add an image. You can enter a URL by using either of the following syntax:
  - A URL that starts with http or https:
    - Syntax: http://host[:port]/path/file or https://host[:port]/path/file.
  - A URL that starts with ftp:
    - Syntax that does not specifies the user: ftp://hostname[:port]/path/file.
    - Syntax that specifies the user: ftp://user:password@hostname[:port]/path/file.
  - A URL that starts with sftp:
    - Syntax that specifies the user identity: sftp://user:password@hostname[:port]/path/file
    - User-identity-free syntax: sftp://user@hostname[:port]/path/file.
  - The absolute path of an image file that is stored on an image storage. The image storage that stores the image file can be an ImageStore image storage.
    Syntax: file:///path/file
  Note:
  - The image file to be added to the destination image storage must exist and the image storage needs to have access to the URL of the image file.
  - If you enter a URL that starts with sftp and does not specify user identity, make sure that you enable password-free SSH login to the server that stores the image file.
  - For the progress bar and resumption from breakpoint features:
    - If you use an ImageStore image storage, a progress bar will appear to display the upload progress. In addition, upload resumption from breakpoints is also supported.
    - If you use a Ceph image storage, a progress bar will appear to display the upload progress. However, upload resumption from breakpoints is not supported.
  - If you specify a URL with the file:/// syntax to add an image:
    - Ceph image storage does not support the file:/// syntax.
    - The three forward slashes (/) in file:/// represents the absolute path of a file on an image storage. For example, if you specify the URL file:///opt/dvd/image-1.4.qcow2, you add the image file named image-1.4.qcow2 in the /opt/dvd path of an image storage to the Cloud.
- Local File: Select a local image file that the current browser can access and upload the image file to the specified image storage. The image storage that stores the image file can be an ImageStore or Ceph image storage.
  Note: If you upload a local image file, the local browser serves as a transfer station. Do not refresh or close the browser or stop management node services. Otherwise, the image addition may fail.

BIOS Mode: Select a BIOS mode. You can select the Legacy or UEFI mode.

Legacy: This mode supports all operating systems (OSs) and ensures stable operation. We recommend you select this mode.
UEFI: If the CPU architecture is AArch64 or MIPS64EL, you must select UEFI. This mode supports Windows and CentOS. Note if you use Windows 7 or Windows Server 2008, make sure that the operating system uses CSM.

Note: Mode mismatch may make VM instances unable to work as expected. Select a mode according to your business needs:

If you add an image in the qcow2 or raw format, select the mode used when the image was created.
If you add an image in the iso format, you can select either of the two modes. OS will be boot based on the selected mode.

If you want to boot the OS of a VM instance in UEFI mode, we recommend that you select a VM image that is created from one of the OS listed in the following table.

OS	BIOS Mode	Supported Versions
Windows	UEFI	Windows 8 or later
Windows	UEFI	Windows 7 Windows Server 2008 R2
Linux	UEFI	CentOS 7.2 CentOS 7.3 CentOS 7.4 or later

If you use a Window-based VM instance such as Windows Server 2012 R2, Windows Server 2016, or Windows 10 that has its OS boot in UEFI mode, the following figure will be displayed after you start the VM instance. In this case, press any key to continue the installation of the OS. Otherwise, the system will enter the UEFI Shell.

Figure 1. Press Any Key to Continue

If you have entered the UEFI Shell, run the following commands to exit the UEFI Shell:
```
Shell> fs0:
FS0:\> dir
FS0:\> cd EFI
FS0:\EFI\> cd BOOT
FS0:\EFI\BOOT\> BOOTX64.EFI
```
Then press any key in a timely manner. Otherwise, the system will reenter the UEFI Shell.

Enable CSM: Optional. Choose whether to use the CSM.
The CSM can only be used for OSs that do not support or partially support the UEFI mode.
Note: For Windows 7 and Windows Server 2008 R2, CSM must be enabled.
Support Elastic Baremetal Instance: Optional. Choose whether the image can be used to create an elastic baremetal instance. If enabled, the image can be used to create an elastic baremetal instance.
Note: When you add an image of an elastic baremetal instance, make sure:
- The image has installed the agent. Otherwise, after you use the image to create an elastic baremetal instance, you cannot open the console or modify the password of the elastic baremetal instance. In addition, you cannot attach a volume or network to the instance or detach a volume or network from it.
- The BIOS mode of the image is the same the system configuration. Default: UEFI. If you want to use Legacy, contact the technical support.

Add Volume Image

On the displayed page, set the following parameters:

Name: Enter a name for the image.
Description: Optional. Enter a description for the image.
Image Type: Select System Image.
Image Format: Select an image format. You can select qcow2, raw or vmdk.
Note: vmdk-formatted image files will be auto-converted to qcow2-formatted files if uploaded to an ImageStore image storage, and to raw-formatted files if uploaded to a Ceph image storage.
Image Storage: Select an image storage.
Image Path: Specify an image URL or upload a local file.

Note: After an image is uploaded, we recommend that check the image integrity according to the MD5 displayed on the image detail page.

ZStack Cloud calculates MD5 of each image uploaded through a URL or a local file, except for images on Ceph image storage.
If you upload an image of the VMDK format, do not use this MD5 for the integrity verification because a VMDK-formatted image file will be auto-converted to a QCOW2-formatted or ROW-formatted file after the upload, which causes an inevitable MD5 change.

Manage an Image

On the main menu of ZStack Cloud, choose Resource Center > Resource Pool > Compute Configuration > Image. Then, the Image page appears.

The following table lists the actions that you can perform on an image.

Action	Description
Add Image	Add an image to an image storage.
Edit Image	Edit the name and description of an image.
Enable Image	Enable a disabled image.
Disable Image	Disable an enabled image. If you disable an image, you cannot use the image to create a VM instance. VM instances created by using the image before the disablement are not affected.
Export Image	Export one or more images. ImageStore and Ceph image storage support image export. Exported images are displayed on the Exported tab. Note: Image exports from ImageStore image storage may take a long time if the image size is great. You can also run the rbd command on a Ceph image storage to export an image from the Ceph image storage. An exported image cannot be exported again.
Change Image Storage	Migrate data between shared storage across networks. Currently, this action is supported across Ceph image storage. Note: To migrate data between Ceph image storage, make sure that the MON nodes of these two image storage are interconnected. If you migrate an ISO image to an image storage of another zone, the VM instances using the image cannot be started. You need to detach the ISO image from the VM instances and then you can start them as expected. After the storage migration, the raw data is reserved in the source image storage. You can go to the details page of the source Ceph image storage and view the data on the Data Cleanup tab. You can Cleanup the raw data. Before you perform this operation, make sure that the storage-migrated data is intact. Cleaning up raw data will make the data unrecoverable. Proceed with caution.
Sync Image	Synchronize images that are stored in one or more image storage to a specified image storage that shares the same monitoring node with the source image storage. Image synchronization is supported only by ImageStore image storage. Note: To ease the pressure on the management network, you can set a network dedicated to image synchronizations by using either of the two methods: Set an image synchronization network when you add an image storage to the platform. Set an image synchronization network on the details page of an image storage. The setting takes effect immediately.
Set Sharing Mode	Set the sharing mode of a resource. The platform provides the following sharing modes: Share Globally: Shares the resource to all projects and accounts. Share to Specified Projects/Accounts: Shares the resource with specified projects and accounts. Not Share: Revokes the resource from projects and accounts to which the resource is shared. If you set Sharing Mode to Not Share for a resource, other projects and accounts cannot use the resource. Note: If you change the Sharing Mode setting of a resource from Share Globally to Share to Specified Projects/Accounts, the resource is visible only to the specified projects or accounts the resource is shared to. If the resource that you share to the specified projects oraccounts is being used by these projects or accounts and then you change the Sharing Mode of the resource, the change does not take effect on the projects or accounts immediately. They can reverse and use the resource until it is released.
Delete Image	Delete an image. A deleted image is displayed on the Recycle Bin tab.
Recover Image	Recover a deleted image. If you recover a deleted image, the image is displayed on the Available tab.
Expunge Image	Expunge a deleted image. You can only expunge an image that is in the recycle bin. Expunging an image also deletes its corresponding exported image. Proceed with caution.
Download Exported Image	Download an exported image. ImageStore and Ceph image storages support this action. The download is implemented by the browser. Note: ImageStore image storage allow you to view the MD5 value of the downloaded image to check whether the downloaded image is the same as the exported image.
Delete Exported Image	Delete an exported image. Note: In an ImageStore image storage, image files are stored in the format of chips. Only when you export an image, or use an image, for example, to create a VM instance will a complete image file be produced. When you delete an exported image, only the complete image file is deleted. The image chips in the image storage remain intact. In a Ceph image storage, image files are stored in the format of blocks. When you delete an exported image, only the exported image file is deleted. The image in the Ceph image storage remain intact.

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