GRUB and BIOS woes

Because of a particular multi hard-drive configuration, I ran into a small issue when installing Fedora.

I had a mixture of classic IDE and SATA drives, and my boot disk were the SATA drives mounted as a RAID 1 array.

In fact, the installation process was smooth: I booted from the install CD and went through the installation normally but GRUB couldn't load when I reboot: I was stuck with a blank screen with the word GRUB in the top left corner.

Discussion

What actually happened is that during install, Fedora assumed the disks were in the following order:

• HD0,0 (/dev/hda): 250GB ATA drive on IDE 0,0
• HD1,0 (/dev/sda): 80GB SATA drive on SATA Controller 0,0
• HD2,0 (/dev/sdb): 80GB SATA drive on SATA Controller 1,0

In the grub.conf file, reference was made to the HD(1,0) as the root disk.
Unfortunately, during the installation process Fedora did not guess the right BIOS numbering of the disks and misconfigured GRUB: while the BIOS was told to boot on the first SATA drive, Fedora gave that disk a different identification.

Resolving the issue after installation

To solve the problem, after booting from the rescue CD, I just had to edit grub.conf and change the references root(hd1,0) to root(hd0,0) and reboot.

In rescue mode, the file system is detected but not mounted.
To edit the grub.cong file, the best is to mount the filesystem properly, then launch the editor:

Make your modifications then exit and reboot (ctrl-alt-del).
Don't forget to remove the rescue CD.

Avoiding the problem

To avoid that problem in the first place, take note of the boot order for your hard disks in your BIOS and then ensure during the Fedora installation process, at the Boot Loader Configuration page that you tick the Configure advanced boot loader options. you will then have the opportunity to change the drive order to match that of the BIOS.