Booting Linux from external USB hard disk

code_monkey · 03-24-2006, 11:59 AM

First off, I must say this is a great forum with a lot of useful information. I look forward to have some lively discussions here.

Here is what I am looking for. I have Fedora Core4 on my hard disk. I have built a Linux Kernel, and a Linux file system, that I have dumped on my external USB hard drive.

I notice that the BIOS is seeing the USB hard drive, and USB hard drive is the first device to try booting from. I think I have made the LILO configuration to boot from the USB drive.

Does anyone have experience doing such a thing, am I nuts to try this?
-CodeMonkey

J.W. · 03-24-2006, 08:23 PM

Welcome to LQ! As long as your BIOS supports booting from a USB device (and you've placed the USB device in the top position in the boot sequence) then it shouldn't be any different than booting from a hard drive or CD. Is there a particular error message that you're getting?

tamoneya · 03-24-2006, 09:27 PM

are you sure that the usb drive is bootable. You might need to add something like syslinux inorder to boot from the usb. This is an article on booting from usb and has a link for syslinux. Might also help to read the article to see if there are any variations from how you did it.

michaelk · 03-25-2006, 08:07 AM

Without knowing error messages it is difficult to determine your problems but Fedora typically does not include USB support in the initial ramdisk (initrd) so the kernel gets lots trying to find the drive at boot. You will need to boot into rescue mode, chroot to the /mnt/sysimage and create a new initrd. The following link shows the details. Be sure to change the USB modules and kernel to match FC4 and your system.

http://www.simonf.com/usb/

code_monkey · 03-27-2006, 12:23 PM

Thanks for the link I will check it out, try it out and report back.

BTW, my bios does see and show the USB hard drive as one of the bootable devices. I have the USB device as the first device to try, then the CD drive, then the internal hard disk with Fedora core4 on it. Everytime I reboot, it starts up Fedora, and I do not see any error messages. I am looking for any verbose mode possible with the BIOS, that I can inspect.
Thanks,
CM

code_monkey · 03-30-2006, 01:54 PM

Alright, why does grub have to rename my disks and partitions with its own names? Beats me.

Anyways, I managed to make changes (to Grub.conf) to show my custom Linux and Grub does see the USB hard disk. I have tried to create various types of file partitions on this USB hard disk. (ext2, primary partition, boot flag set on). I cannot get grub to mount this boot directory. I always get a message saying "cannot mount partition".

Does anyone know what I am missing here?
CM