Re: Wheezy USB Harddrive install grub2 issues

[Indulekha <indulekha@theunworthy.com>]

On Fri, May 11, 2012 at 08:17:41AM -0500, Indulekha wrote:
> On Fri, May 11, 2012 at 07:19:32PM +0800, Bob wrote:
> > 8< snip
> > 
> > >Probably want to skip that "--root-directory" option, unless you're
> > >trying to avoid the mbr for some valid reason...
> > 
> > I've tried it with and without.
> > 
> > >Might want to stick with genuine Debian documentation, too, unless
> > >you're actually running Ubuntu...
> > 
> > I've had trouble finding much Grub2 documentation.
> > http://wiki.debian.org/Grub2
> > is a bit sparse & the GRUB site recommends the Ubuntu documentation
> > http://www.gnu.org/software/grub/grub-documentation.html
> > info grub does produce more & I'm trying to find the relevant bit at
> > the moment.
> > 
> 
> I see...
> 
> Still, using that "--root-directory=/" option will not install grub 
> to your mbr, which is where you want it, and is only useful if you have 
> another boot loader in the mbr with an option to point to your root directory's 
> grub installation. Apparently you don't have such a setup.
> 
> So do this instead:
> 
> First, determine for sure what the designation of your drive really is
> -- could be sda, sdb, hda, etc -- you can use parted to check this if
> you're able to boot into debian, or use a live cd (the debian installer,
> systemrescuecd, etc).
> 
> Then do:
> # grub-install /dev/whatever_disk_you_have_debian_installed_on 
> 
> #update-grub 
> 
> Should work, assuming you haven't done anything to the files in /etc
> /grub.d, and your initrd.img is proper...
> 

Actually, I just remembered something -- depending on how many usb disks
you have plugged in at boot, the /dev/sdx assignment may change, and in 
my experience grub is terrible at dealing with that in spite of
allegedly using uuid... For instance, I have two usb drives, either of 
which may be designated /dev/sdb or /dev/sdc by the system -- if I plug 
both in and try to boot from one of them, it may or may not work as a 
result. If I plug only one in and grub considers it "/dev/sdb" it will 
always work. I don't know why grub should care about the /dev/sdn designation 
if it has access to the uuid, this strikes me as incredibly stupid and would 
seem to indicate that uuid support in grub is only partially implemented 
(i.e still requires "dev/sdn" to be correct or uuid search fails). But that's 
the way it seems to work, nonetheless.

So when you install grub and boot, if possible make sure no other usb
disks are plugged in and see how that goes.

Or maybe *I'm* doing something incorrectly and someone can correct me.
Wouldn't be the first time... 
-- 
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 Indulekha