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View Full Version : Linux bootloader Grub help!?



dereke
11th February 2006, 06:00 AM
I have been trying to install a linux os on a second sata 2 drive (my first is a sata 2 as well) for a couple days now and I have been having problems. My first attempt was gentoo. I got through the whole installation fine except for the bootloader, which absolutely refused to acknowledge any sdb device I had, after making the copy to the mtab dir, making sure I mounted everything correctly, etc... So, I gave up on gentoo.
Now I am trying to install Fedora Core 4. Again, everything went smooth ... untill grub. I installed grub on a boot partition Fedora made on my second sata drive, /dev/sdb. I did not want grub messing around with my functional windows xp MBR, what I used today!, and my plan was to just boot from the second sata whenever I wanted to us Fedora. When I do this, my comp does the usual list of devices, etc... then on the last line (windows screen usually boots after this point) it just says ... GRUB.
I can't help but think about how evil that is... Is there anything wrong with my approach, or anything else, etcc.. I am pretty much as new as they come.

ANY help would be greatly appreciated.
Thanks.

peters
11th February 2006, 06:09 AM
Hmm. I've seen this before. You need to boot from a Rescue CD, then chroot into your system like the dialogs tell you. From there you need to mount /proc, and /boot. What you'll have to do is make sure your /etc/fstab looks good as Grub will use it to decide where your disks are.. Try doing the "grub-install --recheck /dev/sdb". Go through the man pages for grub and grub-install. Watch for errors during the "grub-install". I've gone through something similar recently on my work box. I was booting my system from an SATA PCI add-on card, and the root filesystem was on LVM. Don't worry, it is all do-able, you'll just have to fiddle with it a bit. Man pages, even 'info grub' has some good reading material. Get to know Grub. :)

dereke
11th February 2006, 06:11 AM
Thanks peters, I will give it a shot.

peters
11th February 2006, 06:12 AM
Actually, I just rethought your circumstances, and I *think* that since you are using your BIOS to boot from your 2nd SATA drive, that is what is throwing Grub off. It is thinking your second drive is its boot drive, but BIOS is telling it "no, that is the first drive in the system". Does that make sense? You may want to look at the "map" command within Grub to remap the drives back to what they really look like--when you boot from CDROM during installation or Rescue they will be sda-Windows and sdb-Linux, but when you boot from BIOS/2nd disk, I'm thinking that it makes sda-Linux... Does that make sense? It isn't normal for a PC to 'boot from the 2nd disk in the system'--that is an alien concept to PCs, and problematic.

dereke
11th February 2006, 06:17 AM
Any suggestions to alternate approaches, after knowing that I have a track record of problems with grub :) ?

peters
11th February 2006, 06:20 AM
Boot from floppy. That is what I do. Grub involves keeping pointers to its files on its HD, so "booting Grub from floppy" really only involves like one sector of data (512bytes)--from that point on it is from HD--that makes it very fast. Only trouble is, floppies aren't very reliable. I use the floppy method here at my home. Windows owns the MBR, while Grub is on a floppy disk. 99% of the time I boot from floppy ;)