Question : fatal: open /dev/sdc: no such device or address:  WHY?

I'm in the process of upgrading the disks on my server. (Dell PowerEdge 2300 with Adaptec 2110s controller) Old setup: 4 36G RAID 5  + 1 137G for backups of user folders. I used Acronis Enterprise to make a backup of my partitions to another 137G drive. I replaced the old 36's with 4  new 137G's. Created the new array RAID5, again booted from CD to Acronis, restored the main partition of about 100GB and the 2G swap.

The first problem came when, after the upgrade,  the SCSI controller labeled my RAID array as sdb instead of sda as it used to be. This is because in the physical order of disks inserted into the Dell backplane, the Acronis backup 137G drive is first (slot 0,0), the RAID disks are next (slots 0,1 - 0,4) and the users backup drive, 137G, is last (slot 0,5). Since my boot disk USED to be sda, I booted from a CD, mounted sdb1, chroot to /mnt/sdb1, changed /etc/fstab and /etc/lilo.conf to point to sdb instead. I ran /sbin/lilo and it seemed to write the mbr. It never found LILO with that configuration, I believe (it's tough to remember everything when you try so many different things)

So.... I physically removed drive in slot (0,0) the Acronis backup. It is unneeded now since I restored already. Now, SCSI controller sees my array as sda and backup drive as sdb. I again booted from CD, mounted sda1, chroot-ed to /mnt/sda1 and modified fstab and lilo.conf back to pointing to sda. This time, when I ran /sbin/lilo, I get:

-----------------------------
Warning LBA32 addressing assumed
raid_setup returns offset = 00000000 ndisk = 0
BIOS    VolumeID    Device
Reading boot sector from /dev/sda
Fatal: open /dev/sdc: No such device or address
-----------------------------

 I tried  running lilo -v -v, didn't help

Answer : fatal: open /dev/sdc: no such device or address:  WHY?

I don't use LILO [prefer GRUB myself] so this is a shot in the dark, but is /dev/sdc still in your fstab or lilo.conf anywhere at all? With only 2 drives, /dev/sdc will no longer be in use.

This would be similar to how GRUB installs, it will throw an error if anything is listed in /etc/mtab that does not exist.