Wondering why Debian6.0 VM doesn’t boot under CentOS6/XEN4? We can help you with this!

As part of our Server Virtualization Technologies and Services, we assist our customers with several OnApp queries.

Today, let us see how our support techs help our customers to fix this boot issue.

 

Debian6.0 VM doesn’t boot under CentOS6/XEN4

 
Sometimes the VM will fail to boot under XEN4 if the VMs are built from any older templates before XEN4 support was added.

Here in such situations, we can update these VMs to allow them to boot under XEN4.

The following steps have been completed on a clean install, so there may be specific considerations needed depending on the software running.

Note: It is always better to take a backup before completing these steps on the production VMs.

The booting issue is likely to be due to an issue with grub and we can resolve this by removing the grub.cfg file.
 

Method 1:

1. Firstly, access the VM via SSH.

2. Remove the grub.cfg file.

rm /boot/grub/grub.cfg

3. Now we have to stop the VM.

4. Then migrate to XEN4 HV.

5. Finally, start the VM.

OR
 

Method 2:

1. Firstly, stop the VM.

2. Then we should migrate to XEN4 HV

3. Select ‘Startup in Recovery’ in OnApp UI.

4. Then access the VM via SSH.

5. After that mount /dev/sdb1 /mnt.

6. Then remove the grub.cfg file.

rm -rf /mnt/boot/grub/grub.cfg

7. Finally, select ’Reboot Virtual Machine’ in OnApp UI.

If the above process doesn’t work, we can upgrade from Debian6 to Debian7 using the below steps, which also install a newer kernel that is XEN4 compatible:

1. Check the name and information about the current kernel.

# root@OnApp:~# uname -a
Linux OnApp 2.6.32-24-server #43-Ubuntu SMP Thu Sep 16 16:05:42 UTC 2010 x86_64 GNU/Linux

2. Then cat the file /etc/issue.

# cat /etc/issue
Debian GNU/Linux 6.0 \n \l

3. Then run the following command:

# sed -i ‘s/squeeze/wheezy/g’ /etc/apt/sources.list

4. After that, update the packages by running the following commands:

# apt-get update

# apt-get upgrade

# apt-get dist-upgrade

5. Then take a backup of menu.lst

# cp /boot/grub/menu.lst /boot/grub/menu.lst.old

6. After that edit /boot/grub/menu.lst to remove the previous entries.

7. Then run the halt command.

# halt

8. Now migrate the VM to XEN4 HV and Startup.

9. Check the name and information about the current kernel.

# root@OnApp:~# uname -a

Linux OnApp 3.2.0-4-amd64 #1 SMP Debian 3.2.51-1 x86_64 GNU/Linux

10. Then cat the file /etc/issue.

# cat /etc/issue
Debian GNU/Linux 7 \n \l

[Need further assistance? Contact us now]
 

Conclusion

 
In short, we saw how our Support Techs resolve this ‘Debian6.0 VM doesn’t boot under CentOS6/XEN4’ issue.