GRUB on MBR of Windows-only internal drive, with distros on external drive

Question

I think what I want to do is long and convoluted; then again, it might be somewhat easy, and I'm just overthinking it.

Here's the setup I want to achieve:

• The internal drive (sda) is one giant WinXP partition (sda2), a tiny one for a boot partition (sda1), and the MBR.
• On an external drive (sdb), I will create multiple partitions for several distros. This drive will be either an HDD in an enclosure or something like a WD passport. This will be attached via USB 2.0.

I know it is possible to install grub to the MBR of sda and boot an sdb partition from there. I also know I'll need to edit grub to chainload Windows and list all the distros. However, I have the following questions:

1. If I disconnect sdb and want to select + boot into Windows, is grub going to get upset? In other words, does the grub menu just display what you tell it to, or does it go hunting for those other options immediately and will have problems because some have disappeared?
2. If I disconnect sdb, I'd love for it to still be bootable on another computer. If I have a boot partition on sdb as well as sda, but have my BIOS set to use the internal MBR first, can this be achieved?
3. What if I want to use something pretty like burg or plymouth? How will this change things?

I'm sure the answers are out there somewhere, but I'm finding it hard to Google for!

Answer 1

Keep in mind that GRUB also needs a configuration file and additional files, so you need it in the MBR and it has to access files in some partition just to run. This will ruin 1.

You can either spare some megabytes (if it's even that much) just to have the grub files in sda, or install another bootloader that sits in the MBR (I think lilo does that).

Now for 2., your best choice is probably:

• Set up sdb with a GRUB itself, so that booting through sdb gives you a menu of what is in that disk, and you can use that menu on any computer;
• Set up another GRUB on sda (or another bootloader, if you can't have the files in sda). This one should be independent from sdb and have two entries: chainload into Windows and chainload into sdb (run the other GRUB).

So yes, that setup is achievable, the only thing you may need to spend some time with is finding out what to install on sda if you can't make a tiny partition for GRUB.

(I'm just not sure if GRUB will be able to chainload into an USB drive, I guess that depends partly on GRUB, partly on the BIOS.)