When I tried to do a text-based ugprade from 6.2 to Winston, I got this error message while it was checking for previous installations: "Error mounting hde5: block device required", then an anaconda traceback and the installer gave up. This is probably because hde is on a promise IDE controller whose driver is not built into the kernel. I suspect that when the default IDE driver is used to access the promise IDE card, it can't handle old IDE drives (hde is a very old drive), whereas it can handle such drives when the promise driver is used. Perhaps anaconda should display warnings, not fatal errors, when it can't mount a filesystem that's listed in /etc/fstab.
This feature will be added to our list of requests.
This is not a "feature." It is a bug. I have a valid RedHat installation and yet I cannot use the RedHat upgrade process because of this problem. Yes, there is a workaround (I can comment out hde in /etc/fstab before rebooting to do the upgrade), but that doesn't change the fact that this is a bug and should be treated as such.