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Re: Quick and dirty "debian live" on USB stick.

On Sat, Nov 28, 2009 at 05:19:56PM EST, Chris Jones wrote:
> I'm playing with the idea of copying my laptop's debian lenny partition
> to a USB stick that I can take with me when traveling.
> Since I can't be sure I'll have a machine with available space on the
> HDD or be allowed to partition the drive, what I thought was that I
> could have a bootable system on the USB stick and boot into it pretty
> much as I would off of a live CD. 
> What I had in mind was as simple as:
> . clone the lenny partition to /dev/sda1
> . install grub to /dev/sda
> . make adjustments to the contents of /dev/sda1
> The trouble is that I don't have a machine that can boot off of a USB
> stick to test ahead of time.
> Adjustments that I had in mind:
> . /etc/fstab 
> . /boot/grub/menu.lst (grub.cfg with grub2)
> Naturally, reconfiguring network & internet access, Xorg, printers, etc.
> will be necessary, but they cannot be done ahead of time - although it
> may be possible to make it less of a pain with some preparation and a
> bit of scripting.
> Since I'm running the stock lenny kernel, I shouldn't have problems with
> differences in hardware, but I'm a little concerned that udev might not
> cooperate.
> I'm sure there are other issues, but unfortunately, I can't take the
> trial and error approach.
> So, I was wondering if anyone had done anything comparable, and would
> care to point out possible gotchas?

I now have-a-proof of concept system on the USB stick and have been able
to boot into it by doing the following:

1. Power up the laptop 

2. On the grub2 menu, hit 'c' to escape to a shell of sorts and load the
   USB modules:

   insmod uhci¹
   insmod usbms

   The light on the USB stick should come on telling you it's alive

3. Escape back to the grub menu and Ctrl+X to boot a stanza with
   something like the following:

	 search --no-floppy --fs-uuid --set fb796a23-e59e-4e15-ba92-15f0cd087714
	 linux /boot/vmlinuz-2.6.26-1-686 root=UUID=fb796a23-e59e-4e15-ba92-15f0cd087714 ro
	 initrd /boot/initrd.img-2.6.26-1-686

   where the UUID was determined by:
   # vol_id --uuid /dev/sda1        # blkid on more recent systems

Since I'm running it on the same hardware as the cloned system, it
wasn't too hard, network, X, etc. came up with no problems, just very
slowly, since on top of the thumb drive's limitations, the laptop only
supports USB 1.1. 

The challenges that I see now are getting rid of any customization
specific to my laptop and come up with something generic that will boot
on just about any machine, and set it up so that personal data is
clearly separated from the software and configuration files. 

After that, it's just only a matter of writing a couple of trivial rsync
scripts to keep the data on the HDD and the USB stick in sync'.

Kinda boils down to what Rob Owens initially recommended after all..

Thanks to those who have responded.


¹ There is a bug in grub2 that can be worked around by issuing a
  'debug=uhci,ohci,usbms' command jut before issuing the insmod uhci,
  and resetting it immediately afterwards by issuing a 'debug='

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