Create a custom image by using a snapshot

Restrictions for Linux instances

• Do not load data disk information in the /etc/fstab file. Otherwise, instances created using this image cannot start.
• We recommend that you umount all data disks before creating a custom image, and then use a snapshot to create a custom image. Otherwise, ECS instances that are created based on this custom image may not start.
• Do not upgrade the kernel or operating system version.
• Do not change the system disk partitions. The system disk only supports single root partitions.
• We recommend you check the available space of the system disk to make sure that the system has available space.
• Do not modify critical system files such as /sbin, /bin, /lib, and so on.
• Do not modify the default logon user name root.

Procedure

1. Log on to the ECS console.
2. Select the region.
3. In the left-side navigation pane, click Instances.
4. Find the target instance and click its instance ID, or click Manage in the Actions column.
5. In the left-side navigation pane, click Instance Snapshots. Find the target system disk and then click Create Custom Image in the Actions column.
   
   

   The snapshot must be created from system disks. Data disks cannot be used to create custom images. 

   You can also click Snapshots and Images > Snapshots, and select a snapshot created from a system disk to Create Custom Image.

   
   
   
6. In the Create Custom Image dialog box, complete the following:
   • Confirm the snapshot ID.
   • Enter a name and description of the custom image.
   • Optional. Check Add Data Disk Snapshot, select multiple snapshots of data disks for the image, and click Add to add a data disk.
     Note

     • We recommend that you remove sensitive data from the data disk before creating a custom image to guarantee data security.
     • If the snapshot disk capacity is left blank, an empty disk is created with the default capacity of 5 GiB.
     • If you select available snapshots, the disk size is the same as the size of the snapshots. 

     
     
     
7. Click Create. Then, in the left-side navigation pane, select Snapshots and Images > Images to view the images you have created.

Linux instance image FAQ

If /dev/hda5 is attached to /mnt/hda5, run any of the following three commands to detach the file system.

umount/dev/hda5
umount/mnt/hda5
umount/dev/hda5/mnt/hda5

/Etc/fstab is an important configuration file in Linux. It contains the details of mounting the file system and storage devices upon startup. If you do not want to mount a specified partition when starting the instance, delete the corresponding lines from /etc/fstab. For example, you can delete the following statement to disconnect xvdb1 upon startup: /dev/xvdb1 /leejd ext4 defaults 0 0.

You must make sure that the statement line for automatically attaching mounting data disk has been deleted from the fstab file.

Use the mount command to view the information of all mounted devices. Make sure that the execution results do not contain the information of the data disk partition.

Before creating an image, make sure that the key configuration files listed in the following table have not been modified. Otherwise, the new instance cannot start.