Over the past few months, Linode has been offering upgrades from Xen to KVM virtualization. This would normally be a pain-free experience, unless you’re running CloudLinux. Cloudlinux wants to use its own lve kernel so it wants to boot with grub.
Let’s call our server cloudlinux.linuxos.pro. It’s currently running Xen, but we’re going to upgrade it to KVM.
1. Log into your Linode account.
2. Go to the page listing your current Linodes
3. Click on the ‘Dashboard’ link for the Linode we want to upgrade
5. At the bottom of the next page, it should estimate how long the upgrade will take. Your server will be DOWN during this upgrade. When you are ready, click the “Upgrade to KVM now!” button and go find something to do for the next XX minutes.
6. When it’s complete, you’ll notice that your server didn’t boot afterwards. This is because we need to change a couple things first.
7. Go into the settings (click edit where you have centos picked from the linode’s dashboard) for the Linode and choose a different kernel to boot from. You likely have ‘pv-grub’ selected now. Pick the latest Linode kernel for your flavor (32 or 64 bit) and reboot it.
8. Let it boot – it’s going to boot, but your lve kernel won’t be running, so cloudlinux would be useless if you kept it like this.
9. Once up, ssh as root into your server and edit the /boot/grub/grub.conf file.
ttyS0 (if exists)
10. Go back into the kernel settings in the Linode dashboard, change the kernel to ‘Grub Legacy’ and reboot again.
More information in the Linode KVM reference.