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What Do I Do If the Disks of an ECS Created from a CentOS Image Cannot Be Found?

Symptom

Generally, this is because the xen-blkfront.ko module is not loaded during the startup. You need to modify OS kernel startup parameters. Figure 1 shows the startup screen after the login to the ECS.

Figure 1 Startup screen

Solution

Perform the following operations to modify OS kernel boot parameters:

These operations must be performed after the OS starts. You are advised to modify kernel boot parameters in the ECS used for creating the image.

1. Run the following command to log in to the OS:
   lsinitrd /boot/initramfs-`uname -r`.img |grep -i xen

   • If the command output contains xen-blkfront.ko, contact the customer service.
   • If no command output is displayed, go to 2.
2. Back up the GRUB configuration file.
   • If the ECS runs CentOS 6, run the following command:

     cp /boot/grub/grub.conf /boot/grub/grub.conf.bak

   • If the ECS runs CentOS 7, run the following command:

     cp /boot/grub2/grub.cfg /boot/grub2/grub.cfg.bak

3. Use the vi editor to open the GRUB configuration file. Run the following command (using CentOS 7 as an example):

   vi /boot/grub2/grub.cfg

4. Add xen_emul_unplug=all to the default boot kernel.
   

   Search for the line that contains root=UUID= and add xen_emul_unplug=all to the end of the line.

   menuentry 'CentOS Linux (3.10.0-229.el7.x86_64) 7 (Core) with debugging' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-229.el7.x86_64-advanced-bf3cc825-7638-48d8-8222-cd2f412dd0de' {
           load_video
           set gfxpayload=keep
           insmod gzio
           insmod part_msdos
           insmod ext2
           set root='hd0,msdos1'
           if [ x$feature_platform_search_hint = xy ]; then
             search --no-floppy --fs-uuid --set=root --hint='hd0,msdos1'  bf3cc825-7638-48d8-8222-cd2f412dd0de
           else
             search --no-floppy --fs-uuid --set=root bf3cc825-7638-48d8-8222-cd2f412dd0de
           fi
           linux16 /boot/vmlinuz-3.10.0-229.el7.x86_64 root=UUID=bf3cc825-7638-48d8-8222-cd2f412dd0de xen_emul_unplug=all ro crashkernel=auto rhgb quiet  systemd.log_level=debug systemd.log_target=kmsg
           initrd16 /boot/initramfs-3.10.0-229.el7.x86_64.img
   }

5. Press Esc, enter :wq, and press Enter to exit the vi editor.
6. Create an image using the ECS, upload and register the image on the cloud platform.

Parent topic: ECS Creation

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