Grub rescue - error: unknown filesystem

Опубликовано: 15 Июнь 2019
на канале: Roel Van de Paar

158

Grub rescue - error: unknown filesystem

The Question: I have a multiboot system set up. The system has three drives. Multiboot is
configured with Windows XP, Windows 7, and Ubuntu - all on the first drive. I
had a lot of unpartitioned space left on the drive and was reserving it for
adding other OSes and for storing files there in the future.
One day I went ahead and downloaded Partition Wizard and created a logical NTFS
partition from within Windows 7, still some unpartitioned space left over.
Everything worked fine, until I rebooted the computer a few days later.
Now I'm getting:
error: unknown filesystem.
grub rescue＞
First of all I was surprised not to find any kind of help command, by trying:
help, ?, man, --help, -h, bash, cmd, etc.
Now I'm stuck with non-bootable system. I have started researching the issue
and finding that people usually recommend to boot to a Live CD and fix the
issue from there. Is there a way to fix this issue from within grub rescue
without the need for Live CD?
UPDATE
By following the steps from https://askubuntu.com/questions/90471...
commands-typed-to-grub-rescue, I was able to boot to initramfs prompt. But not
anywhere further than that.
So far from reading the manual on https://help.ubuntu.com/community/
Grub2#Rescue_Mode_.28.27.27grub_rescue.3E.27.27.29_Booting, I was able to see
my drives and partitions using ls command. For the first hard drive I see the
following:
(hd0) (hd0,msdos6) (hd0,msdos5) (hd0,msdos2) (hd0,msdos1)
I now know that (hd0,msdos6) contains Linux on it, since ls (hd0,msdos6)/ lists
directories. Others will give "error: unknown filesystem."
UPDATE 2
After the following commands I am now getting to the boot menu and can boot
into Windows 7 and Ubuntu, but upon reboot I have to repeat these steps.
ls
ls (hd0,msdos6)/
set root=(hd0,msdos6)
ls /
set prefix=(hd0,msdos6)/boot/grub
insmod /boot/grub/linux.mod
normal
UPDATE 3
Thanks Shashank Singh, with your instructions I have simplified my steps to the
following. I have learned from you that I can replace msdos6 with just a 6 and
that I can just do insmod normal instead of insmod /boot/grub/linux.mod. Now I
just need to figure out how to save this settings from within grub itself,
without booting into any OS.
set root=(hd0,6)
set prefix=(hd0,6)/boot/grub
insmod normal
normal
UPDATE 4
Well, it seems like it is a requirement to boot into Linux. After booting into
Ubuntu I have performed the following steps described in the https://
... (Please watch the video for the full question)

Solutions Sample (Please watch the whole video to see all solutions, in order of how many people found them helpful):

== This solution helped 5 people ==
Use:
1. set prefix=(hdX,Y)/boot/grub. Use the values determined earlier.
Example: If the Ubuntu system is on sda5, enter:
set prefix=(hd0,5)/boot/grub
2. set root=(hdX,Y). Example: set root=(hd0,5)
3. insmod normal. Attempt to load the normal module.
4. normal
We basically need GRUB to know where the /boot/grub folder is. If this is not
working, I guess doing a GRUB install from a boot CD is a good option.

== This solution helped 3 people ==
Funny, I also had the same problem an hour ago!
Anyway, this is what I did.
1. Load ubuntu:
set root=(hd0,6)
set prefix=(hd0,6)/boot/grub
insmod normal
normal
since your ubuntu is installed in 6 right?
2. run terminal:
sudo -i to access root
grub-install --root-directory=/mnt/ /dev/sda
sudo update-grub
sudo grub-install /dev/sda

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