Hard drive weirdness.

[David Gibb]

I'm experiencing some weird behaviour with my disk drives, and I was
hoping someone might be able to give me some hints.

I have an oldish computer (AMD athlon 850) that I wanted to use as a
file server. I had a 20GB PATA drive lying about, and I bought a
promise sata300 tx4 card plus 2 500GB sata drives that were on
special.

I hooked the 2 sata drives to the card, and the PATA drive to the
motherboard's controller, and then I installed ubuntu server 8.04 on
the 20GB drive. Everything went smoothly until I rebooted after the
install, when it couldn't find the system drive. I played around with
the boot settings in the bios until I found that none of the 'IDE-X'
settings worked, but 'SCSI' did. Once ubuntu started up, I found that
the 20GB pata drive showed up as /dev/sdc, and the 2 500GB SATA drives
showed up as /dev/sda and /dev/sdb. I found this to be a touch weird,
but everything seemed to be working so I left it as is.

I then installed software RAID 1 on the two 500GB drives, then LVM on
top of them, samba, etc, etc. Everything works great. I still wanted
to simulate a drive failure, so that I could verify that the RAID
mirroring was working, and to figure out which physical drive was
which. Here's when the trouble started.

When I pulled sata drive #1, I get a blank screen with a blinking
cursor. No GRUB, no nothing. When I pulled sata drive #2, I get "GRUB
Hard disk error". When I pull both disks, I get a "System disk not
found" error.

I guess my questions are as follows:

1) Does anyone know why my PATA drive isn't showing up as /dev/hda?
2) I guess I could possibly explain the "GRUB Hard disk error" if the
absence of a drive caused the drive number to change, but I don't know
why the absence of the other drive causes a blank screen.
3) Any idea how I should tinker with this system so that I can still
boot it in case one of the raid drives fails?

Thanks!
David