On Wed, Mar 16, 2011 at 09:45:13AM -0500, Troy Dawson wrote:
> I have a full distro on a USB stick. It's currently Fedora 13 instead
> of SL6, but the procedure is the exact same.
>
> Do a normal install with the USB hard drive plugged in and selected as
> the main hard drive, and with all your partitions on it. The only thing
> you have to be careful of is where grub is put, and what order grub
> thinks the drives are.
In my experience, trying to USB-boot Linux using SL5 GRUB is futile. GRUB gets
hopelessly confused by the ordering of BIOS "hard drives" - which seems to
change between cold and warm reboots.
BTW, on the machines where I looked into it, one cannot "select USB hard drive
as the main hard drive" on a permanent basis - if you ever boot the machine
with the USB drive accidentally unplugged or powered down, I see BIOS settings
reverting back to whatever crazy random order you use and GRUB will fail
to boot until you go back to the BIOS setup screen and change the settings.
The best I can tell, the root of the problem is with GRUB insisting on booting
from disk 0 (or whatever number is specified in grub.conf) instead of continuing
to use the boot disk selected by the BIOS (as SYSLINUX/EXTLINUX seems to do).
This strategy of booting from BIOS disk number selected in some config file
may have worked well in the days of hardwired "primary master" IDE disks and
mostly continues to function with hardwired SATA disks (i.e. fails on ASUS A8N-E mobos
where ordering of SATA ports by BIOS and Linux is not the same), but completely
makes no sense with dynamically assigned USB disks (if I have 2 USB disks, which
one is disk 0? Yes, it is in the USB enumeration order, so it is deterinistic,
but if I plug in a 3rd USB disk, USB enumeration order may change and GRUB will
not boot).
Anyhow, according to http://www.gnu.org/software/grub/ GRUB has
been abandoned, so why are we still using it?!? In contrast, SYSLINUX/EXTLINUX/PXELINUX
is still in active development. (Yes, there is GRUB-2, if you can find it, but SL5 is not
using it).
K.O.
>
> http://www.scientificlinux.org/distributions/6x/installing/boot.loader.configuration.html
>
> On SL6, be sure to select "Change device" and make sure your USB drive
> is marked as the "First BIOS drive". Then make sure it's set to install
> the boot loader on the MBR of our USB hard drive.
> http://www.scientificlinux.org/distributions/6x/installing/large/boot.loader.5.png
--
Konstantin Olchanski
Data Acquisition Systems: The Bytes Must Flow!
Email: olchansk-at-triumf-dot-ca
Snail mail: 4004 Wesbrook Mall, TRIUMF, Vancouver, B.C., V6T 2A3, Canada
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