[plug] How to install grub on an external disk, so it boots as primary.

[Gavin Chester]

On Sat, 2007-07-14 at 11:45 +0800, Gavin Chester wrote:
> On Sat, 2007-07-14 at 08:52 +0800, Mike Holland wrote:
> > Hi folks,
> > I'm far from home with a CD-less laptop and a USB external drive full of 
> > data.
> > I have copied Linux and my essential data from laptop to the external
> > drive, and wish to make it bootable as a backup, in case the primary fails.
> > 
> >   However I cannot see how to install GRUB so that it
> > can be swapped to the primary drive. Ordinarily, I would boot off
> > CD with the new HDD installed, but this laptop has no optical drive,
> > and I'm out in the wilderness without another Linux PC to use.
> >   The laptop BIOS will not boot from USB-mass-storage.
> > 
> > So, Is there a way to get grub to install on sdb for booting as sda?
> > Or should I try LILO?
> 
> This isn't a rebuke to RTFM, but have you read the grub manual? I found
> it very comprehensive when I had grub trouble several years ago. Can you
> install grub on the primary drive (either in the primary partition or
> mbr) to point to the usb drive, or is that not an option? Again, the
> grub manual will walk you thru' how to install grub where you want. I
> may stand corrected, but I think you can install grub on any partition,
> as long as it points to the correct booting partition containing your
> kernel. 

Re-reading my own post, perhaps I missed your point, but then it wasn't
that clear :-/ You sound like you perhaps want to have a bootable mirror
copy of sda on usb-mounted sdb. Is that closer to the mark? In that case
forget what I said first time and look at backup solutions like Mondo,
rdiff-backup and the like, done _wthout_ compression. Then when the
primary drive fails (if you feel that's imminent) the pop it out and put
the reserve in. Wouldn't that work? Just trying to redeem myself here
after misunderstanding your post ;-)

Gavin