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Updated on 2024-03-05 GMT+08:00
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Constraints

This section describes the constraints on using IMS.

Table 1 Constraints on creating a private image

Item

Constraint

Maximum number of private images that can be created in a region

50

If you need more, submit a service ticket to increase your quota. For details, see How Do I Increase the Image Quota?

Maximum number of concurrent tasks for creating private images

40

NOTE:

Currently, only one image can be created in each task.

Creating a system disk image from an ECS or BMS
  • The ECS must be in the Stopped or Running state.
  • The BMS must be in the Stopped state and must be booted from an EVS disk rather than a local disk.

Creating a data disk image from an ECS
  • The ECS must be in the Stopped or Running state.
  • A data disk image can be used to create only one data disk at a time.

Disk capacity
  • The system disk capacity of an ECS or a BMS used to create a system disk image must be no greater than 1 TB. If it is greater than 1 TB for an ECS, you can only use the ECS to create a full-ECS image.
  • The data disk capacity of an ECS used to create a data disk image must be no greater than 1 TB. If it is greater than 1 TB, you can only use the ECS to create a full-ECS image.

Creating a full-ECS image from an ECS or a CSBS or CBR backup
  • The ECS must be in the Stopped or Running state.
  • A CSBS or CBR backup can be used to create only one full-ECS image at a time.
  • A full-ECS image can only be replicated across regions.
  • A full-ECS image is shareable with other tenants only when it is created from a CBR backup or from an ECS that has never had a CSBS backup.
  • A full-ECS image cannot be exported, published in Marketplace, or replicated within a region.
Table 2 Constraints on importing a private image

Item

Constraint

Importing a system disk image from an external image file

For details about constraints on external image files, see Preparing an Image File (Windows) or Preparing an Image File (Linux).

Importing a system disk image from an ISO file
  • Register the ISO file as an ISO image, use the ISO image to create a temporary ECS, install an OS and related drivers on the ECS, and use the ECS to create a system disk image.
  • The ISO image cannot be replicated, exported, or encrypted.

Importing a data disk image from an external image file

The data disk capacity can be 40–2048 GB, and it must also be at least as big as the data disk in the image file.

Image format

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

Image size

The image size cannot exceed 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 through fast import.
Table 3 Constrains on sharing images

Item

Constraint

Maximum number of tenants an image can be shared with

System disk image or data disk image: 128

Full-ECS image: 10

Maximum number of shared images that a tenant can receive

No limit

Private image status

Normal

Image sharing

Encrypted images, images published in the Marketplace, and full-ECS images created from a CSBS backup cannot be shared with others.

Region
  • You can share images only within the region where they reside. To make an image available in a different region, replicate the image to the region and then share it.
  • There are constraints on the region when cloud servers are created from a shared image. For example, a shared image can be used to create cloud servers only in the same region.
Table 4 Constraints on replicating an image

Item

Constraint

Maximum size of an image

128 GB

The image size cannot exceed 300 GB if you replicate an image from the CN South-Guangzhou, CN East-Shanghai1, CN East-Shanghai2, or CN North-Beijing4 region to another region. In other cases, it cannot exceed 128 GB.

Maximum number of concurrent replication tasks per tenant

5

Private image status

Normal

Replicating images within a region
  • Full-ECS images cannot be replicated within the same region.
  • Private images created using ISO files do not support in-region replication.

Replicating images across regions
  • A new replication task can be created only after the previous replication task is complete.
  • Encrypted images do not support cross-region replication.
Table 5 Constraints on exporting an image

Item

Constraint

Maximum size of an exported image

1 TB

Images larger than 128 GB only support fast export.

NOTE:

In some regions, an image larger than 128 GB can be exported normally (not fast export).

For details about fast export, see Comparison Between Import and Fast Import, and Between Export and Fast Export.

Formats of exported image files

VMDK, VHD, QCOW2, ZVHD, and ZVHD2

Private image status

Normal

Exporting an image
  • Encrypted images cannot be exported through fast export.
  • An image can only be exported to a Standard bucket that is in the same region as the image.
  • The following private images cannot be exported:
    • Full-ECS images
    • ISO images
    • Private images created from a Windows, SUSE, Red Hat, Ubuntu, or Oracle Linux public image
    • Private images created from a Marketplace image
  • The image size must be less than 1 TB. Images larger than 128 GB support only fast export.
    NOTE:

    In some regions, an image larger than 128 GB can be exported normally (not fast export).
Table 6 Constraints on other image operations

Operation

Item

Constraint

Encrypting an image

Creating an encrypted image from an encrypted ECS or an external image file
  • An encrypted image cannot be shared with other tenants, published in the Marketplace, or replicated across regions.
  • The key used for encrypting an image cannot be changed.

Deleting images

Private image status

A published private image cannot be deleted.

Creating cloud servers from an image

Number of cloud servers that can be concurrently created using a system disk image

Recommended value: ≤ 100

Tagging an image

Maximum number of tags that can be added to a private image

10

Other Constraints

  • If an ECS is frozen due to overdue payment, it cannot be used to create a private image. You must renew the ECS before using it to create a private image.
  • A private image created from an x86 ECS cannot be used to create a Kunpeng ECS or change the OS of a Kunpeng ECS.
  • When you use an external image file to create a private image and select x86 for Architecture, the private image cannot be used to create a Kunpeng ECS or change the OS of a Kunpeng ECS.
  • A private image containing a 32-bit OS cannot be used to create an ECS with larger than 4 GB of memory because the total available address space for a 32-bit OS is 4 GB.