Recover From Grub Failure
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-install /dev/sda
If there are no error messages, you should be able to reboot now.