You can create a custom image from a snapshot that contains the operating system and data of an Elastic Compute Service (ECS) instance. Then, you can use the custom image to create multiple identical instances.
Prerequisites
Background information

Before you create custom images from snapshots, take note of the following items:
- Notes on snapshots used to create custom images:
- A custom image can be created from a system disk snapshot or from a system disk snapshot and one or more data disk snapshots. Data disk snapshots alone cannot be used to create custom images.
- Both encrypted and unencrypted snapshots can be used to create custom images.
- If the ECS instance from which a snapshot was created expires or is released, the custom image created from the snapshot and the ECS instance created from the image are not affected.
- Notes on custom images:
- Custom images cannot be used across regions. To use custom images across regions, you can copy custom images from one region to another. For more information, see Copy a custom image.
- The billing method of custom images is independent of that of the ECS instances from which the custom images were created and that of the ECS instances created from the custom images. For example, custom images created from subscription instances can be used to create pay-as-you-go instances.
- Notes on ECS instances created from custom images:
- You can upgrade the configurations of ECS instances created from custom images, such as vCPUs, memory, bandwidth, and disks.
- You can replace the operating systems of ECS instances created from custom images. The custom images are not affected and remain usable. For more information, see Replace the operating system of an instance by using a non-public image.
- Network connection may fail to be established for some ECS Linux instances in virtual private clouds (VPCs) that are created from custom images. This may be caused by the configurations in /etc/sysconfig/network. For more information, see How to solve unreachable network errors when a VPC-type instance is created from a custom image.
- Recommendations for data security:
- For information about how to enhance the security of custom images, see Security suggestions for Alibaba Cloud custom images.
- Delete sensitive data from a snapshot in advance to enhance data security.
Procedure
What to do next
After the custom image is created, you can perform operations described in the following
topics: