Recover From Grub Failure: Difference between revisions

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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.
During to the upgrade from 3.x to 4.x, I found myself without a working grub and unable to boot. Monitor shows:
* grub rescue >
 
I attempted to use the proxmox 4.1 install disk, but found it had a bug where the prompt would not accept input.
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.
You'll need a ISO for a 64 bit version of Ubuntu or Debian Rescue CD, must be 64 bit.


Boot ubuntu off the ISO.  We do not want to install ubuntu, just run it live off the ISO/DVD.
Boot Ubuntu/Debian off the ISO.  We do not want to install Ubuntu/Debian, 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.
First We need to activate LVM and mount the the root partition that is inside the LVM container.
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Mount all the filesystems that are already there so we can upgrade/install grub.  Your paths may vary depending on your drive configuration.
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 mkdir /media/RESCUE
*sudo mount /dev/pve/root /media/USB/
*sudo mount /dev/pve/root /media/RESCUE/
*sudo mount /dev/sda1 /media/USB/boot
*sudo mount /dev/sda1 /media/RESCUE/boot
*sudo mount -t proc proc /media/USB/proc
*sudo mount -t proc proc /media/RESCUE/proc
*sudo mount -t sysfs sys /media/USB/sys
*sudo mount -t sysfs sys /media/RESCUE/sys
*sudo mount -o bind /dev /media/USB/dev
*sudo mount -o bind /dev /media/RESCUE/dev


Chroot into your proxmox install.
Chroot into your proxmox install.
*chroot /media/USB
*chroot /media/RESCUE


Then upgrade grub and install it.
Then upgrade grub and install it.

Revision as of 10:58, 21 August 2016

During to the upgrade from 3.x to 4.x, I found myself without a working grub and unable to boot. Monitor shows:

  • grub rescue >

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 or Debian Rescue CD, must be 64 bit.

Boot Ubuntu/Debian off the ISO. We do not want to install Ubuntu/Debian, 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/RESCUE
  • sudo mount /dev/pve/root /media/RESCUE/
  • sudo mount /dev/sda1 /media/RESCUE/boot
  • sudo mount -t proc proc /media/RESCUE/proc
  • sudo mount -t sysfs sys /media/RESCUE/sys
  • sudo mount -o bind /dev /media/RESCUE/dev

Chroot into your proxmox install.

  • chroot /media/RESCUE

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.

Credit: https://www.nerdoncoffee.com/operating-systems/re-install-grub-on-proxmox/

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