[SOLVED] How to fix grub after moving root partition?

gandrusz · 05-15-2010, 05:03 PM

Hi,

Because I am using one of the new WD disks I am trying to aling my root partition with the real sectors, as described here:

http://community.wdc.com/t5/Desktop/...m-p/10920#M631

So I copied all files to a temp location, deleted my partition (/dev/sda3), recreated it a few cylinders later (same name) and copied the files to the newly created partition. But now when I try to boot, I get my old grub menu but after selecting my kernel version it hangs... Any idea how I can fix it?

brucehinrichs · 05-15-2010, 05:16 PM

Use a LiveCD to boot, open a terminal and type: sudo grub-install. Select where you want grub installed (probably to the MBR, but if you are dual-booting maybe to /), and reboot. If that doesn't work, post back, as there are alternative solutions.

zuzoa · 05-15-2010, 05:22 PM

Are you sure the partition was recreated as /dev/sda3? If it changed, you'll have to edit your /boot/grub/grub.conf or /boot/grub/menu.lst with the new info. Please post the contents of this file and the output of 'fdisk -l'.

gandrusz · 05-15-2010, 05:22 PM

Hi,

Yes, I have grub installed in MBR (because of dual boot as you suggested). I did actually run grub-install from Knoppix (sorry, should have mentioned in the initial post) and grub itself IS running fine, its just hanging after I select my configuration from the list (I haven't tried booting to Windows yet).

brucehinrichs · 05-15-2010, 05:26 PM

The command blkid (as root) will give you the current UUID number for that (actually all) partition. Check that number against the UUID in your /boot/grub/menu.lst file. If the numbers don't match, change the value in /boot/grub/menu.lst to the value blkid returned, then try booting again.

EDIT: If you're certain it is /dev/sda3, you can use blkid /dev/sda3 to get the UUID for that partition only.

gandrusz · 05-15-2010, 05:27 PM

Quote:

Originally Posted by zuzoa

Are you sure the partition was recreated as /dev/sda3? If it changed, you'll have to edit your /boot/grub/grub.conf or /boot/grub/menu.lst with the new info. Please post the contents of this file and the output of 'fdisk -l'.

knoppix@Microknoppix:~$ fdisk -l

Disk /dev/sda: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x24b4d5f6

Device Boot Start End Blocks Id System
/dev/sda1 1 13 102400 7 HPFS/NTFS
Partition 1 does not end on cylinder boundary.
/dev/sda2 13 25497 204696576 7 HPFS/NTFS
/dev/sda3 * 25498 37654 97642496 83 Linux
/dev/sda4 37655 182401 1162680277+ 5 Extended
/dev/sda5 37655 38870 9767488+ 82 Linux swap / Solaris
/dev/sda6 38871 182401 1152912726 83 Linux

zuzoa · 05-15-2010, 05:36 PM

Well it looks like your linux partition is still /dev/sda3. Can you post the contents of your /boot/grub/menu.lst (or grub.conf) file?

gandrusz · 05-15-2010, 05:46 PM

Quote:

Originally Posted by brucehinrichs

The command blkid (as root) will give you the current UUID number for that (actually all) partition. Check that number against the UUID in your /boot/grub/menu.lst file. If the numbers don't match, change the value in /boot/grub/menu.lst to the value blkid returned, then try booting again.

EDIT: If you're certain it is /dev/sda3, you can use blkid /dev/sda3 to get the UUID for that partition only.

The UUIDs were different indeed (I didn't find menu.lst, updated grub.cfg instead). Currently I get the following error messages:

Code:

mount: mounting /dev on /root/dev failed: No such file or directory
mount: mounting /sys on /root/sys failed: No such file or directory
mount: mounting /proc on /root/proc failed: No such file or directory
/init: line 253: can't open /root/dev/console: no such file
... Kernel Panic....

My current grub.cfg:

Code:

knoppix@Microknoppix:~$ cat /media/sda3/boot/grub/grub.cfg 
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by /usr/sbin/grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
  load_env
fi
set default="0"
if [ ${prev_saved_entry} ]; then
  set saved_entry=${prev_saved_entry}
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z ${boot_once} ]; then
    saved_entry=${chosen}
    save_env saved_entry
  fi
}
insmod ext2
set root='(hd0,3)'
search --no-floppy --fs-uuid --set c2612767-032d-43a2-b414-aac0a0f7d5f5
if loadfont /usr/share/grub/unicode.pf2 ; then
  set gfxmode=640x480
  insmod gfxterm
  insmod vbe
  if terminal_output gfxterm ; then true ; else
    # For backward compatibility with versions of terminal.mod that don't
    # understand terminal_output
    terminal gfxterm
  fi
fi
insmod ext2
set root='(hd0,3)'
search --no-floppy --fs-uuid --set c2612767-032d-43a2-b414-aac0a0f7d5f5
set locale_dir=($root)/boot/grub/locale
set lang=en
insmod gettext
set timeout=5
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
insmod ext2
set root='(hd0,3)'
search --no-floppy --fs-uuid --set c2612767-032d-43a2-b414-aac0a0f7d5f5
insmod png
if background_image /boot/grub/moreblue-orbit-grub.png ; then
  set color_normal=black/black
  set color_highlight=magenta/black
else
  set menu_color_normal=cyan/blue
  set menu_color_highlight=white/blue
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
menuentry "Debian GNU/Linux, with Linux 2.6.32-trunk-686" --class debian --class gnu-linux --class gnu --class os {
	insmod ext2
	set root='(hd0,3)'
	search --no-floppy --fs-uuid --set c2612767-032d-43a2-b414-aac0a0f7d5f5
	echo	Loading Linux 2.6.32-trunk-686 ...
	linux	/boot/vmlinuz-2.6.32-trunk-686 root=UUID=c2612767-032d-43a2-b414-aac0a0f7d5f5 ro  quiet
	echo	Loading initial ramdisk ...
	initrd	/boot/initrd.img-2.6.32-trunk-686
}
menuentry "Debian GNU/Linux, with Linux 2.6.32-trunk-686 (recovery mode)" --class debian --class gnu-linux --class gnu --class os {
	insmod ext2
	set root='(hd0,3)'
	search --no-floppy --fs-uuid --set c2612767-032d-43a2-b414-aac0a0f7d5f5
	echo	Loading Linux 2.6.32-trunk-686 ...
	linux	/boot/vmlinuz-2.6.32-trunk-686 root=UUID=c2612767-032d-43a2-b414-aac0a0f7d5f5 ro single 
	echo	Loading initial ramdisk ...
	initrd	/boot/initrd.img-2.6.32-trunk-686
}
menuentry "Debian GNU/Linux, with Linux 2.6.32-3-686" --class debian --class gnu-linux --class gnu --class os {
	insmod ext2
	set root='(hd0,3)'
	search --no-floppy --fs-uuid --set c2612767-032d-43a2-b414-aac0a0f7d5f5
	echo	Loading Linux 2.6.32-3-686 ...
	linux	/boot/vmlinuz-2.6.32-3-686 root=UUID=c2612767-032d-43a2-b414-aac0a0f7d5f5 ro  quiet
	echo	Loading initial ramdisk ...
	initrd	/boot/initrd.img-2.6.32-3-686
}
menuentry "Debian GNU/Linux, with Linux 2.6.32-3-686 (recovery mode)" --class debian --class gnu-linux --class gnu --class os {
	insmod ext2
	set root='(hd0,3)'
	search --no-floppy --fs-uuid --set c2612767-032d-43a2-b414-aac0a0f7d5f5
	echo	Loading Linux 2.6.32-3-686 ...
	linux	/boot/vmlinuz-2.6.32-3-686 root=UUID=c2612767-032d-43a2-b414-aac0a0f7d5f5 ro single 
	echo	Loading initial ramdisk ...
	initrd	/boot/initrd.img-2.6.32-3-686
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/11_Windows ###
menuentry ���Windows 7��� {
    insmod ntfs
    set root=(hd0,2)
    search --no-floppy --fs-uuid --set 5e5001485001287b
    chainloader +1
}
### END /etc/grub.d/11_Windows ###

### BEGIN /etc/grub.d/30_os-prober ###
menuentry "Windows 7 (loader) (on /dev/sda1)" {
	insmod ntfs
	set root='(hd0,1)'
	search --no-floppy --fs-uuid --set 5e5001485001287b
	chainloader +1
}
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

zuzoa · 05-15-2010, 05:54 PM

Sometimes it helps to add the partition, (hd0,2), before the paths like /boot/vmlinuz and /boot/initrd, so they become "(hd0,2)/boot/vmlinuz-2.6.32-trunk-686 root=UUID=c2612767-032d-43a2-b414-aac0a0f7d5f5 ro quiet"

brucehinrichs · 05-15-2010, 05:57 PM

I hope this isn't it

, but the filesystem may have been corrupted. From the liveCD terminal try:

Code:

e2fsck -fyv /dev/sda3

to check the filesystem.

brucehinrichs · 05-15-2010, 06:02 PM

@zuzoa: Does grub2 use the same naming scheme as grub legacy (/dev/sda3 = (hd0,2)) or did they change it to correspond to the /dev scheme (/dev/sda3 = (hd0,3))? I honestly don't remember, as I still use legacy.

EDIT: The reason I ask is OPs grub.cfg file says "set root='(hd0,3)'"

zuzoa · 05-15-2010, 06:07 PM

Quote:

Originally Posted by brucehinrichs

@zuzoa: Does grub2 use the same naming scheme as grub legacy (/dev/sda3 = (hd0,2)) or did they change it to correspond to the /dev scheme (/dev/sda3 = (hd0,3))? I honestly don't remember, as I still use legacy.

EDIT: The reason I ask is OPs grub.cfg file says "set root='(hd0,3)'"

Honestly, I'm not sure. I still use legacy as well. If one doesn't work, try the other :P I would guess it's probably the same convention to avoid confusion, but I don't know.

Edit: I just realised that this might be the cause of the problems. OP, Please change the line to "set root='(hd0,2)'" and try booting.

brucehinrichs · 05-15-2010, 06:14 PM

From this link:

Quote:

In other words, devices are still numbered from 0, but partitions start with 1. For example, this means that sda1 is now (hd0,1) and NOT (hd0,0) as before!

So, /dev/sda3 = (hd0,3), and zuzoa's (good) suggestion amended:

Quote:

Sometimes it helps to add the partition, (hd0,3), before the paths like /boot/vmlinuz and /boot/initrd, so they become "(hd0,3)/boot/vmlinuz-2.6.32-trunk-686 root=UUID=c2612767-032d-43a2-b414-aac0a0f7d5f5 ro quiet"

gandrusz · 05-16-2010, 01:20 AM

Quote:

Originally Posted by zuzoa

Honestly, I'm not sure. I still use legacy as well. If one doesn't work, try the other :P I would guess it's probably the same convention to avoid confusion, but I don't know.

Edit: I just realised that this might be the cause of the problems. OP, Please change the line to "set root='(hd0,2)'" and try booting.

Tried that and it completely doesn't work now (so I think they must have changed the convention)

gandrusz · 05-16-2010, 01:22 AM

Quote:

Originally Posted by brucehinrichs

I hope this isn't it

, but the filesystem may have been corrupted. From the liveCD terminal try:

Code:

e2fsck -fyv /dev/sda3

to check the filesystem.

The filesystem looks alright:

Code:

root@Microknoppix:/home/knoppix# e2fsck -fyv /dev/sda3
e2fsck 1.41.9 (22-Aug-2009)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information

  307025 inodes used (5.03%)
      56 non-contiguous files (0.0%)
     240 non-contiguous directories (0.1%)
         # of inodes with ind/dind/tind blocks: 16891/186/0
 2494089 blocks used (10.22%)
       0 bad blocks
       1 large file

  239379 regular files
   25314 directories
       0 character device files
       0 block device files
       0 fifos
     411 links
   42323 symbolic links (36640 fast symbolic links)
       0 sockets
--------
  307427 files