Preparing an Image File

You need to prepare an image file that meets the platform requirements.

Note

Table 1 Linux image file requirements

Image File Property

Requirement

OS

  • SUSE, Oracle Linux, Red Hat, Ubuntu, openSUSE, CentOS, Debian, Fedora, EulerOS, and NeoKylin

  • 32-bit or 64-bit

  • The OS cannot be bound to specific hardware.

  • The OS must support full virtualization.

For details about the supported OS versions, see External Image File Formats and Supported OSs. These OSs support automatic configuration. For details, see What Will the System Do to an Image File When I Use the File to Register a Private Image? For other OSs, check and install the VirtIO driver (see Installing Native KVM Drivers). On the image registration page, select Other Linux. After the image is imported, whether the system is started depends on the driver integrity.

Image format

VMDK, VHD, QCOW2, RAW, VHDX, QED, VDI, QCOW, ZVHD2, and ZVHD

Image size

Maximum file size: 128 GB

If the image size is between 128 GB and 1 TB, convert the image file into the RAW or ZVHD2 format and import the image using fast import.

Network

The NIC must be set to DHCP and files must be deleted from the network role directory. Otherwise, the ECS startup or network capability will be abnormal. For details, see:

The following value-added operations are optional:

Tool

You are advised to install Cloud-Init.

Cloud-Init is an open-source tool for cloud instance initialization. When creating ECSs from an image with Cloud-Init, you can use user data injection to inject customized initialization details (for example, an ECS login password) to the ECSs. You can also configure and manage a running ECS by querying and using metadata. If Cloud-Init is not installed, you cannot apply custom configurations to the ECSs. You will have to use the original password in the image file to log in to the ECSs.

For details, see Installing Cloud-Init.

Driver

Installing native KVM drivers

File system

Other requirements

  • Currently, images with data disks cannot be created. The image file must contain only the system disk, and the system disk size must be between 1 GB and 1024 GB.

  • The initial password in the image file must contain uppercase letters, lowercase letters, digits, and special characters (!@$%^-_=+[{}]:,./?).

  • The boot partition and system partition must be on the same disk.

  • Generally, the boot mode is BIOS in an image. Some OS images support the UEFI boot mode. For details, see "OSs Supporting UEFI Boot Mode" in Image Service Management User Guide.

  • The image file cannot be encrypted, or ECSs created from the registered image may not work properly.

  • The /etc/fstab file cannot contain automatic mounting information of non-system disks. Otherwise, the login to the created ECS may fail.

  • If the external image file uses LVM as the system disk, ECSs created from the private image do not support file injection.

  • If the VM where the external image file is located has been shut down, it must be a graceful shutdown. Otherwise, a blue screen may occur when the ECS created from the private image is started.