usb hard disk

[Torfinn Ingolfsen]

On Wed, 31 Jan 2007 15:40:13 +0100
Zoran Kolic <zkolic at sbb.co.yu> wrote:

> This is not strictly "stable", unless I make a mistake and shoot
> myself in the foot.
> I have 6.2 amd64 with mobo asus k8n nforce3 250. This box I'd like to
> use as host for usb hdd, that should contain linux install (debian
> 4.0, when comes out). Two worlds have not to interfare in any
> meaning. I hesi- tate to take internal freebsd hdd out of the box.
> Here's the plan: plug external hdd to usb, change bios option to boot
> from cd, install debian on sda, change bios option to boot from usb
> disk. Lilo or grub should be installed on external disk, without
> writing any data on inter- nal hdd. Is it possible at all?

Yes, as long as the bios of your machine can boot from an usb hard
drive, this should be possible. I have done this with several machines.

It works like this: 
(usb hard drive connected to machine)
- you boot machine (on some machines you can press a special key to
  bring up a bios boot menu)
- you select usb hard drive from bios boot menu
- bios loads boot loader (either Grub, Lilo, FreeBSD boot loader, 
  or whatever boot loader you use)
- boot loader from usb hardr drive does its thing (either booting an OS
  or displaying a boot menu)

So far I am only aware of one caveat; the FreeBSD boot loader doesn't
work on all machines. For example, I have an Acer Aspire 5672 laptop
here were it doesn't work.

I am going to try out grub on that laptop to see if it works better,
but haven't found the time yet.

> I'm aware that partition table on external hdd could have data for
> freebsd disk, but nothing has to be writen on internal disk. No boot

No problem, it is the bios which loads from whatever disk you choose.
If you make a mistake (for example when installing an OS on the usb
hard drive) and suddenly overwrite your inernal hard drive, that's your
fault.
(If your'e afarid of this happening, simply disconnect the internal
drive when installing on the usb hard drive.)


> manager needed, all has to be done using bios. What obstacle would I
> see doing that?

None, as long as your bios and the boot loader of choice can boot from
usb hard drive.

HTH
-- 
Regards,
Torfinn Ingolfsen,
Norway