I've read the GRUB manual from top to bottom, and I'm still can't get it to boot my new Debain 3.1 install.

Here's the situation. I started with one hard drive (/dev/sda, S-ATA) with only one partition, NTFS, for Windows XP. I've added a new hard drive (/dev/sdb, S-ATA) with the idea of creating a couple ext3 partitions for Linux distros.

I thought I'd start with Debian. During installation, I was asked if I wanted to install GRUB onto the MBR of my first hard drive. Fearing the potential of GRUB to make my Windows drive unbootable, I declined (the right decision too, as the default install of GRUB attempts to boot Windows incorrectly). I instead chose to install GRUB onto the MBR of the second hard drive. I would change my bios settings to boot from either the first or second hard drive.

However, when I try to boot from the second hard drive (containing Debian), the command...

root (hd1,0)

...raises an error that the boot sector has an unknown file system 0x7 (incorrect, that's not even the right code for ext3, is it?). Then, the command...

kernel /boot/blah-blah root=/dev/sdb1 ro

...throws ERROR: 17 (can't mount the partition). What does this "ro" even mean? It's not in the GRUB manual.

Sorry for the long post, but does anyone have advice for me? How can I edit the current menu.lst...

root (hd1,0)
kernel /boot/blah-blah root=/dev/sdb1 ro
boot

...to actually boot my new Debian install? (And by "blah-blah", I do mean the correct location of the kernel. I just can't remember it right now.)

In what way do you edit the BIOS to boot from either drive. If it involves changing the designations Master and Slave, the what you are doing is making the Debian drive Master (hd0,0), and the xp drive Slave (hd1,0). When you try to boot Debian, you get 'unknown filesystem 0x7', which is xp.

You would probably have to edit menu.lst and change 'root (hd1,0)' to 'root (hd0,0)' to make it work by changeing BIOS settings.

My opinion: it's easier to leave the BIOS alone. Install grub to the MBR of the Master drive (sda). Grub (and Debians implementation of grub) should be sophisticated enough to detect the xp installation during Debian installation, and correctly write the menu.lst entry for xp to allow booting without interruption.

Installing grub to the MBR after Debian is already installed won't write the menu.lst config for xp. Editing the menu.lst and making the entries is easy enough. Just read the grub manual. The examples there should work to get xp booting with minimum trouble.

Thanks! That was the problem. Had only I known that 0x7 was the code for NTFS, this thread might well have been averted.

For all of those who might run into the same problem, I'll elaborate on the solution. First, what I had been doing is setting the "Hard Drive Boot Priority" setting in my system BIOS. While this changes the order of the drives as far as GRUB is concerned, it does not confuse the actual OS's once loaded (and while the kernel is loading). To get around all of this, I change my menu.lst entry to be...

root (hd0,0)
kernel /boot/blah-blah root=/dev/sdb1 ro
savedefault
boot

(Note the "sdb1". "sda1" will not work in this situation, as the kernel will always go by the original drive order.)

Thanks again.