reinstalling grub MBR on first drive

Bill Davidsen davidsen at
Fri Nov 27 00:44:58 UTC 2009

Colin Brace wrote:
> Hi all,
> Several weeks ago, I installed a new motherboard in my Fedora system. During
> the switchover, the SATA drives (I have five) were reconnected in a slightly
> different order. As a result, the grub menu wasn't displayed; rather I was
> dumped into the grub prompt and had to boot manually (root..., kernel...
> initrd... boot).
> Just now, I tried to fix it by reconnecting the SATA drives in the order I
> think they should, but I have succeeded only in making things worse. Now I
> don't even get a the grub prompt; just an empty screen.
> Yes, I've googled this, yes, there lots of hits, but I can't seem to figure
> out what I need to do. From what I understand, the MBR of the first drive
> needs to point to the drive with the OS. In my case, the OS is on /dev/sdb.
> So, there needs to be something in the MBR on /dev/sda pointing to
> /dev/sdb1, which is /boot, no? Still, I seem to be missing part of the
> picture. Simply put, what do I need to do to be able to boot my system
> again?
Boot from a rescue CD, find and mount the boot and root partitions if the rescue 
doesn't, go into the original root and run grub-install. See the man page for 

Bill Davidsen <davidsen at>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot

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