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    Elastic Compute Service:Manage images FAQ

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    Elastic Compute Service:Manage images FAQ

    Last Updated:May 15, 2026

    Image creation

    Image copy

    Encrypted image

    Image sharing

    Image import

    Image export

    Image deletion

    Image usage

    Appendix

    Can I create a custom image from an ECS data disk?

    No. Custom images can only be created from system disk snapshots. However, you can include data disk snapshots when you create a custom image from a snapshot.

    Image creation progress and duration

    View the creation progress on the Images page in the ECS console. Creation time depends on instance disk size. The image becomes available after all disk snapshots are created. See Create a custom image from an instance.

    When should I copy an image?

    A custom image is available only in its source region. Copy an image to:

    • Deploy applications across multiple regions.

    • Migrate an instance to another region.

    • Use a custom image across regions.

    • Change the encryption status, such as encrypting the system disk.

    See Copy a custom image.

    Which images can I copy?

    Only custom images can be copied. Public images and Marketplace images cannot be copied.

    Image copy duration

    Copy duration depends on network speed and task queue depth.

    For large images (such as over 2 TiB), copy the snapshots to the destination region first, then create an image from those snapshots. This is faster than copying the image directly. Copying snapshots across regions incurs data transfer and storage fees. See Snapshot pricing.

    Copy a Marketplace-based custom image across regions

    You can copy a Marketplace-based custom image to the destination region only if the source Marketplace image is available there. Otherwise, the copy fails.

    Copy a Marketplace-based custom image across regions

    Share images between Alibaba Cloud sites

    Image sharing between the China site (aliyun.com) and the international site (alibabacloud.com) is not supported.

    Risks of using shared images

    • Shared images risk data leaks and software exposure. Before sharing, verify the image contains no sensitive data or critical security software. Recipients can create instances and further custom images from the shared image, propagating the data.

    • Alibaba Cloud does not guarantee the integrity or security of images from other accounts. Use shared images at your own risk. Only use images shared by trusted accounts, and verify security after creating an instance from a shared image.

    • The image owner can view sharing status and delete the image. If the owner deletes a shared image, you can no longer reinitialize system disks of instances created from it.

    Reshare a shared image

    No. Create a custom image from the shared image, then share the new image.

    Share an image across accounts and regions

    These steps can be performed in any order: share the image with the destination account, and copy the image to the destination region.

    Encrypt system disks with KMS, Terraform, or Packer

    • ECS system disks support encryption with the default Key Management Service (KMS) key or a bring-your-own-key (BYOK) key. See Encrypt a system disk.

    • In Packer, use the image_encrypted parameter. See Alicloud Image Builder.

    • In Terraform, use the encrypted parameter. See alicloud_disks.

    Limitations on copying encrypted images

    • KMS is activated.

    • When you copy an encrypted image, you must select Encrypt during copy as the copy type.

    • To use a custom key, create a key in KMS first.

    Permissions for sharing encrypted images

    First, use RAM to create a role named AliyunECSShareEncryptImageDefaultRole and grant the required permissions. Then share the encrypted image with other Alibaba Cloud accounts or enterprise accounts via your resource directory. See Share an encrypted custom image.

    Image import progress and duration

    View import progress in the custom images list of the destination region or on the Tasks page.

    Import duration depends on image file size and concurrent task count. See Import a custom image.

    Replace an expired BYOL license

    Change the instance operating system to replace the BYOL image with an Alibaba Cloud image.

    Use an internal OSS URL for image import

    No. The OSS object address must be a public URL generated by sharing the file. An internal OSS URL causes the import task to fail.

    Convert an ISO file for ECS

    ECS does not support ISO image files. Convert an ISO file to a supported format first.

    1. Use a tool such as VirtualBox to create a local image from the ISO file.

    2. Convert the image to a supported format, such as RAW, VHD, QCOW2, or VMDK.

    See Import a custom image.

    How do I import a local image file?

    See Import a custom image.

    Permissions for uploading images to OSS

    • With an Alibaba Cloud account, you can directly upload image files to OSS.

    • As a RAM user, the Alibaba Cloud account holder must grant you the required permissions to manage the OSS bucket.

    Download an image to a local machine

    Export a custom image to download it to your local machine.

    Bootability of exported images on other platforms

    Exported images are not guaranteed to be bootable on other platforms, but you can mount the disk image to access its data.

    How do I export a public image?

    Only custom images can be exported. To export a public image, first create a custom image from it, then export the custom image.

    Delete a custom image that is in use

    You must force delete the image.

    Consequences of deletion:

    • The recipient can no longer find the shared image in the ECS console or via API.

    • The recipient can no longer use the image to create instances or replace system disks.

    • Instances already created from the shared image cannot have their system disks reinitialized.

    See Delete a custom image.

    Resolve the "ImageId is used" deletion error

    This error occurs because the image is in use. Force delete it. Force deletion does not affect existing instances, but you cannot reinitialize the system disk of instances created from this image. See Delete a custom image.

    Resolve system disk auto-resize failures

    Auto-resize may fail if cloud-init is not installed or fails to run, or if the file system is unsupported. If auto-resize fails, manually resize the disk.

    Why comment out mount entries for custom images

    Creating an instance from a custom image may fail to mount a data disk if:

    • The instance has no data disk.

    • The data disk is new and not yet partitioned or formatted.

    • The mount entries in /etc/fstab of the custom image are not commented out.

    This failure occurs when an instance with an unpartitioned data disk is created from a custom image whose /etc/fstab contains uncommented mount entries.

    1. The data disk is not partitioned.Data disk not partitioned

    2. The mount entries in /etc/fstab are not commented out.Disk mount entries

    3. The instance tries to mount the disk per /etc/fstab but fails because the disk is not partitioned.Mount disk failure

    Leave mount entries uncommented only if the data disk is created from a snapshot that is already partitioned and formatted.

    If the issue persists, submit a ticket for technical support.

    Enable I/O optimization for custom images

    Some custom images do not support I/O optimized instances. To enable this, submit a ticket and specify the image name.

    Configure and use a private Docker repository

    Docker provides an open source project, docker-registry, on GitHub for building private image repositories.

    To start a Docker registry with OSS support, download docker-registry from GitHub, then install the OSS driver with pip install docker-registry-driver-alioss.

    1. Run the Docker registry: 

       docker run -e OSS_BUCKET=<your_oss_bucket_name> -e STORAGE_PATH=/docker/ -e OSS_KEY=<your_oss_accesskey_id> -e OSS_SECRET=<your_oss_accesskey_secret> -p 5000:5000 -d chrisjin/registry:ali_oss

    2. Configure config.yml: 

      storage: alioss
storage_path: _env:STORAGE_PATH:/devregistry/
oss_bucket: _env:OSS_BUCKET[:default_value]
oss_accessid: _env:OSS_KEY
oss_accesskey: _env:OSS_SECRET

    3. Start the Docker registry: 

       DOCKER_REGISTRY_CONFIG=[your_config_path] gunicorn -k gevent -b 0.0.0.0:5000 -w 1 docker_registry.wsgi:application

    If the issue persists, submit a ticket for technical support.

    OS naming conventions for custom images

    OS names without a minor version number, such as Centos_64-bit, originate from imported on-premises images. Custom images created from these images inherit this naming convention.

    OS names with a minor version number, such as Centos_7.9 64-bit, indicate that the image was created from an Alibaba Cloud ECS instance.