Recover From Grub Failure

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Revision as of 16:55, 14 March 2016 by Term (talk | contribs)
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During to the upgrade from 3.x to 4.x, I found myself without a working grub and unable to boot. I attempted to use the proxmox 4.1 install disk, but found it had a bug where the prompt would not accept input.

You'll need a ISO for a 64 bit version of Ubuntu, I used 14.04 LTS.

Boot ubuntu off the ISO. We do not want to install ubuntu, just run it live off the ISO/DVD.

First We need to activate LVM and mount the the root partition that is inside the LVM container.

  • sudo vgscan
  • sudo vgchange -ay

Mount all the filesystems that are already there so we can upgrade/install grub. Your paths may vary depending on your drive configuration.

  • sudo mkdir /media/USB
  • sudo mount /dev/pve/root /media/USB/
  • sudo mount /dev/sda1 /media/USB/boot
  • sudo mount -t proc proc /media/USB/proc
  • sudo mount -t sysfs sys /media/USB/sys
  • sudo mount -o bind /dev /media/USB/dev

Chroot into your proxmox install.

  • chroot /media/USB

Then upgrade grub and install it.

  • grub-upgrade
  • grub-install /dev/sda

If there are no error messages, you should be able to reboot now.