Self-contained external USB

[Guest]

So. I wanted to try to install Kubuntu on an external hard drive
1) So I don't mess up anything on my laptop
2) So I can bring Kubuntu from computer to computer with ease

I downloaded the CD, installed it on my external hard drive, and when it asked me where to install GRUB MBR, I selected the external hard drive.

I restarted my machine, booted from USB, and was prompted with your basic GRUB screen. I selected Kubuntu, and got the error:
Error 17: Cannot mount selected partition

Searching the forums, it was suggested I download Super Grub. I did so, booted to the CD, selected my external hard drive, got the same GRUB screen as I got above, and it worked!

I'm not sure what the GRUB on my external is doing different than this 'Super Grub' CD.

Any ideas on how I can make my external bootable?

Thanks,
Erik

[Qqmike]

Re: Self-contained external USB

“Any ideas on how I can make my external bootable?”

Yes.

You already installed GRUB to the MBR of the external USB HDD. That's good.

Next, you simply need to edit the boot menu, /boot/grub/menu.lst, located in the Kubuntu (on the external USB HDD). When you use the USB drive, you (usually) shutdown the PC, hook up your external drive, turn on the PC, enter BIOS and select the USB drive as the boot drive, and then the USB drive boots up (using the code/partition table in the USB drive). Whenever this happens (booting from the USB), the BIOS and GRUB both see your USB drive as hard drive hd0, just for this “session.” Thus, your boot menu for Kubuntu (on the external USB HDD) must refer to Kubuntu as being on drive hd0.

So, hook up the external USB drive (and turn it On so it will be recognized by BIOS), and also re-boot from the Kubuntu live CD, then access (mount) and edit /boot/grub/menu.lst (in the Kubuntu on the external USB HDD) so your Kubuntu boot stanza looks like this:

*** Begin Automagic kernels list
etc etc etc
title Kubuntu on external USB
root (hd0,y)
kernel /boot/vmlinuz-etc root=UUID=etc ro quiet splash {or whatever options etc}
initrd /boot/initrd.img-etc
quiet {or whatever}

Do the same with the Recovery mode and with Memtest

*** End Automagic kernels list

------> NOTE: if you wish to boot any other OS from this USB boot menu, you will have to modify each OS's boot stanza so the root (hdx,y) is correct.


The KEY is the root (hd0,y) statement – that's the only statement you need to edit here.
hd0 means Kubuntu is on hard drive 0;
y = partition that Kubuntu is on (if you put Kubuntu on the first partition of the USB, then y is zero; if on the second partition of the USB, then y is 1; etc—counting starts at zero);

That should do it.


Here's some principles, but you really don't need to do a bunch of reading (unless you want to):

How To Make GRUB Thumb Drive
http://kubuntuforums.net/forums/inde...opic=3081748.0
Reply #1: How to install K/Ubuntu 7.04 to an external USB hard disk drive (HDD), Reply #1
(I've done this with 7.10, too, many times )

How To GRUB Methods - Toolkit
http://kubuntuforums.net/forums/inde...opic=3081671.0
--- Reply #1: HOW To: Change the Default Operating System (Also: Changing the timeout, boot menu, and other tips) Reply #1
(This is a general GRUB how-to, and it does explain how to edit menu.lst from a live CD)

[Guest]

Re: Self-contained external USB

Whenever this happens (booting from the USB), the BIOS and GRUB both see your USB drive as hard drive hd0, just for this “session.”

Ah ha! That explains everything. I thought it might have had to do with the menu.lst file... but every time I booted via a CD it looked like the linux partition location was correct.

Thus, your boot menu for Kubuntu (on the external USB HDD) must refer to Kubuntu as being on drive hd0.

This worked great! Thanks for your help!!

[Qqmike]

Re: Self-contained external USB

Good job! (Congratulations on understanding what's going on and being able to roll with the punches here with just a small tip.)
Welcome to the forum!

[Qqmike]

Re: Self-contained external USB

gameshints, btw, fyi, BOIS (and therefore GRUB, since GRUB sees hard drives the same way BIOS sees them) both see the boot drive as hd0: At boot time, whatever drive BIOS booted from is seen as hd0, even if it is a flash drive, external USB HDD (your situation), or an internal drive.