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

[Mike Holland]

Gavin Chester wrote:

> Re-reading my own post, perhaps I missed your point, but then it wasn't
> that clear :-/ 

Sorry Gavin - that was a terrible post. The travellers' belly must have 
affected me more that I realised (my excuse and I'm sticking etc).
I should have posted the exact "grub-install" command I used, and the
error message. I thought grub was refusing to install on a device
that the BIOS said was not bootable.  But I may have made some silly
typo, because I just tried again and it worked.

   # grub-install --root-directory=/media/disk /dev/sdb
   Probing devices to guess BIOS drives. This may take a long time.
   Installation finished. No error reported.

Then I copied /boot/grub/menu.lst, edit it for different partition 
numbers, hibernate, swap hard disks, boot and yes! grub loads.

> You sound like you perhaps want to have a bootable mirror
> copy of sda on usb-mounted sdb. Is that closer to the mark?

Yes. Not exactly a mirror, as the backup drive is smaller.
I manually copied all the important things, and had trouble
with grub, but fixed now.

And in hindsight, i think there is still something to be said for
separate boot partitions.

 > look at backup solutions like Mondo, rdiff-backup and the like,

Thanks, I'll look at those.
Mike