[PLUG] Borked grub!

Derek Loree drl at drloree.com
Sun Nov 16 07:33:16 UTC 2008


On Sat, 2008-11-15 at 17:16 -0800, John Jason Jordan wrote:
> On Sat, 15 Nov 2008 17:22:03 -0700
> Stuart Jansen <sjansen at buscaluz.org> dijo:
> 
> > On Sat, 2008-11-15 at 15:48 -0800, John Jason Jordan wrote:
> > > I have a passing familiarity with grub, but this has me flummoxed. The
> > > ghost of 2.6.24-19 refuses to leave. I'm about to call in a priest. Any
> > > suggestions?
> > 
> > I'm guessing that you accidentally created a new /boot and installed the
> > new grub to to your new /boot partition instead of the MBR.
> > 
> > If that is the case, the following should fix your system:
> > 
> > sudo grub-install /dev/sda
> 
> Thanks for the idea. But I still haven't got it fixed.
> 
> First, *I* didn't create a new boot, but the Hardy > Intrepid upgrade may have. Is there a way to find out where the MBR is?
> 
> Second, the boot partition is a RAID partition (dev/md1). From man grub-install it says 
> 
>  INSTALL_DEVICE can be a GRUB device name or a system device filename.
> 
> So I did "sudo grub-install /dev/md1." It appeared to work, but when I rebooted I still got only the 2.6.24-19 option.
> 
> Here is what the menu.lst file says in the automagic section:
> 
> title		Ubuntu 8.10, kernel 2.6.27-7-generic
> root		(hd0,0)
> kernel	/boot/vmlinuz-2.6.27-7-generic root=/dev/md1 ro quiet splash
> initrd	/boot/initrd.img-2.6.27-7-generic
> 
> And then there is a recovery mode for the same kernel, followed by memtest86+, and that's all.
> 
> When I look at the boot menu during the boot process (hitting esc when the grub menu comes up) I see that the boot option is also set to (hd0,0) and root is dev/md1.
> 
> Still confused.
> 
The boot loader needs to be loaded into the MBR of the drive that the
BIOS initializes, 99.99% of the time this is the "Primary" hard drive.
Your RAID device is not the device that the BIOS tries to start, in fact
your RAID device is only a virtual device composed of several real
devices.  One of those devices is the device that the motherboard
starts.  Usually this would be /dev/sda unless it is old school and then
it would most likely be /dev/hda.  Notice that neither of these devices
are partitions, so even though GRUB will install on a partition, or a
hard drive, only a hard drive will be given the boot-up signal by the
motherboard.

Try running "sudo grub-install --root-directory=/dev/md1 /dev/sda"
or  "sudo grub-install --root-directory=/dev/md1 /dev/hda"; one of these
should place GRUB in the MBR of the primary hard drive.

Good Luck,
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-- 
Derek Loree




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