When trying to upgrade RHL 5.0 to RHL 5.2, I ran into a problem because some of the partitions were accessed via a DPT scsi card. (The / /usr and /home partitions were on /dev/hda. There seems not to be support for the DPT card in the installer kernel, so the upgrade failed with the error "mount failed, block device required" The fix I used was to boot back into old operating system, edit fstab so that these scsi-based partitions didn't mount, then upgrade. But what would I have done if I needed one of the partitions on the DPT controller for the upgrade?
We are aware of this problem and will hope to have a solution for the next release.