A helpful guide on how to recover from a broken grub install and also how to repair your suse system with access to the system's yast utility.
Original article from caf4926 on the Opensuse forums. This guide will teach you how to rescue your grub on SLE 12, Leap and Tumbleweed as well as get access to YAST to fix any broken runlevels and other modifications.
Boot the Rescue from the DVD or the RescueCD. This should be the same Arch as the installation: ie; 32 bit or 64 bit... Also includes the steps to get YAST working by mounting sys and proc before chroot.
Once the DVD rescue gets to 'login', type: root from there I run fdisk -l to confirm my HD partitition order.
My root partition is /dev/sda3 in this guide and is where /boot is.
See below for more instuctions for a seperate /boot partition
We need to mount root (for me that's sda3)
Now mount / (sda3) with
mount /dev/sda3 /mnt
You might need to add the following if there is a BTRFS filesystem with subvolumes
mount /dev/sda3 /mnt -o subvol=@
For installations with an EFI partition we will mount that as well. In this example i will use sda1
mount /dev/sda1 /mnt/boot/efi
To mount the other devices next do
mount --bind /dev /mnt/dev
mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys
For EFI you need to rbind
mount --rbind /sys /mnt/sys
Then chroot
chroot /mnt
Your prompt changes to: Rescue:/>
Here type:
mkinitrd
Note Mkinitrd has now been depreciated so do the following command:
dracut -f
Another Note is that you might need to run a different command to rebuild everything. This seemed needed with custom kernels.
dracut -f --regenerate-all
Then do
Traditional Setup: grub2-mkconfig -o /boot/grub2/grub.cfg
EFI Setup: grub2-mkconfig -o /boot/efi/EFI/opensuse/grub.cfg
grub2-install /dev/sda
Then to reboot you type exit and then reboot as follows.
exit
reboot
This also allows one to have access to YAST hence the binding of sys and proc before chroot.
If you use LVM please check this post: https://forums.opensuse.org/showthread.php/478290-article-re-install-grub2-dvd-rescue-3 For Encrypted LVM and in check this forum guide out: https://forums.opensuse.org/showthread.php/536654-how-to-re-install-grub-chroot-for-encrypted-lvm
You can see it all here: https://dl.dropbox.com/u/10573557/Gr...ect/rescue.jpg
N.B: This method should also work from a DVD or the RescueCD and doesnt matter if version type is different. You can use a Opensuse Leap disc to rescue a SLES install and vice versa.
The discs should be the same Architecture as the installation: ie; 32 bit or 64 bit..USE DVD OR RESCUE CD
If you have a seperate /boot partition you will also need to mount that before you chroot. in this example /boot will be in /dev/sda2
mount /dev/sda2 /mnt/boot
Continue as above with the mounting of /dev to /mnt/dev.
Sources: caf4926. “Re-Install Grub2 from DVD Rescue.” OpenSUSE Forums RSS, OpenSUSE, 12 Sept. 2012, forums.opensuse.org/content.php/128-Re-install-Grub2-from-DVD-Rescue.
“Reinstalling GRUB Bootloader from the Rescue System.” SUSE, SUSE , 30 Apr. 2021, https://www.suse.com/support/kb/doc/?id=000016528. Document ID: 000019909
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