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View Full Version : [ubuntu] grub error .. unknown filesystem grub repair


patrick11ty
April 5th, 2011, 06:55 PM
hello .. my dual boot (ubuntu 10.10 & win7) has given a grub error that I would like some help solving. on boot the computer now says:

error: unknown filesystem
grub rescue>

I would really like to get both systems up and running ..
I have dug around a few hours and tried some steps i found here (https://help.ubuntu.com/community/Grub2#Command Line and Rescue Mode) but honestly I am afraid I will lose the win7 if I have not already if I go further. from the grub rescue I have found the grub here:

ls (hd0,msdos7)/boot/grub
which is weird I think as the results from the boot info script (below) seems to indicate it should be on msdos6.. help would be greatly appreciated.


Boot Info Script 0.55 dated February 15th, 2010

============================= Boot Info Summary: ==============================

=> Grub 2 is installed in the MBR of /dev/sda and looks on the same drive in
partition #6 for (,msdos6)/boot/grub.
=> Syslinux is installed in the MBR of /dev/sdb

////clip////
wilee-nilee
April 5th, 2011, 07:29 PM
Grub 2 is installed in the MBR of /dev/sda and looks on the same drive in
partition #6 for (,msdos6)/boot/grub.

Your install is in sda7 follow this link in reinstalling the grub2 bootloader from a live cd to the mbr.
https://help.ubuntu.com/community/Grub2#Reinstalling%20GRUB%202

Same page as your link; above, section 12.
drs305
April 5th, 2011, 07:40 PM
If everything is intact you may be able to do this from the rescue prompt:


set prefix=(hd0,7)/boot/grub
set root=(hd0,7)
insmod (hd0,7)/boot/grub/linux.mod
linux /vmlinuz root=/dev/sda7 ro
initrd /initrd.img
boot

If it boots run:

sudo grub-install /dev/sda
sudo update-grub
patrick11ty
April 5th, 2011, 07:52 PM
it worked! was surprised during the process that it didn't recognize or need me to specify a /home or /boot but I guess it didn't need it as it seems to be fully functional (win7 as well seems to be working).

thanks so much for your help.
patrick11ty
April 5th, 2011, 07:53 PM
If everything is intact you may be able to do this from the rescue prompt:


set prefix=(hd0,7)/boot/grub
set root=(hd0,7)
insmod (hd0,7)/boot/grub/linux.mod
linux /vmlinuz root=/dev/sda7 ro
initrd /initrd.img
boot

If it boots run:

sudo grub-install /dev/sda
sudo update-grub
thanks for the idea .. but I was at the time booted into the live usb. hopefully it can help someone else in the future.

thanks for your help!