Re: Booting a USB hard drive
Peter Bonucci (peter.bonucci@verizon.net on 2011-05-09 13:21 -0700):
> On Monday, May 09, 2011 10:25:44 am Camaleón wrote:
> > On Mon, 09 May 2011 09:02:45 -0700, Peter Bonucci wrote:
> > > On Sunday, May 08, 2011 10:17:47 pm Klaus Wolf wrote:
> > >> I think that this is not a debian related problem, The BIOS of
> > >> your Laptop has to bi figured to use the USB-Drive for boot.
> > >
> > > The BIOS of this computer boots from all of my other USB drives.
> > > The problem is this particular drive model (Western Digital My
> > > Passport Essential.)
> > >
> > > Booting a USB drive when the drive and computer don't cooperate
> > > is an old problem. People solved it under Debian years ago. I
> > > just don't know how they solved it and search engines didn't help.
Slightly offtopic, but I feel the urge to correct you here: the
bootloader is for its disk I/O completely dependent on what the bios
provides. Therefore, if the bios does not provide int13 services for
USB disks (and older bioses didn't), there is nothing the bootloader
can do about it, except loading its own USB drivers.
Now that isn't the case here, because other disks boot fine. But it's
not a problem that's been "solved in Debian".
> > There shouldn't be any mistery for this. If the BIOS is capable of
> > booting from a USB device but the drive where Debian has been
> > installed is bypassed by the BIOS, I would check that:
> >
> > 1/ GRUB is installed into the MBR of the USB disk.
>
> I believe I did this while installing Debian on the USB drive. How
> can I verify it?
$ file -s /dev/sdX
where X is your usb drive. If GRUB2 is installed in the MBR, you should
see "x86 boot sector; GRand Unified Bootloader, stage1" or something
like that. Don't know if grub-legacy has a similar signature.
> > 2/ Partition where "/boot" is installed is marked with the bootable
> > flag (if there is no dedicated partition for "/boot", then "/"
> > should be the one to be marked).
As an aside: this is hardly ever necessary. Grub does not use the
active (bootable) flag for anything. The MS-DOS bootloader does use the
active flag, so you need it if grub is NOT installed in the mbr. And in
that case, the partition onto which grub is installed should be marked
active.
> > 3/ The system can be properly booted from an external source (i.e.,
> > using a LiveCD of SuperGrubDisk).
>
> The laptop boots from its own hard disk.
:) not an external source. But you already indicated that other USB
disks work fine.
> Under SuperGrubDisk, "List devices/partitions", Grub doesn't see the
> USB drive. None of the other options boot the drive.
How do you boot SGB? From the internal drive, or another usb
stick/netboot? Because if it's not via USB, it's not too surprising
that usb support is not loaded by the bios.
> Selecting the experimental USB support doesn't seem to change
> anything.
laptops are not known for their strict adherence to hardware standards,
so this isn't very surprising. Do you have a USB Legacy option in your
bios? It might help in this case (although it's primarily meant for
input devices, not disks)
Good luck,
Arno
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