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 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 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 (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. For details about how to convert the image file format, see Converting the Image Format Using qemu-img-hw. For details about fast import, see Fast Import of an Image File.

**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 KooGallery, and full-ECS images created from a CSBS backup cannot be shared with others.
Region	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
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.

**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. 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 an Ubuntu public image The image size must be less than 1 TB. Images larger than 128 GB support only 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 others. 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

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.