8.0-RELEASE upgrade -- no files visible

[A. Wright]

Some further information . . .

recap: failures mounting filesystems that were not in
dangerously dedicated mode . . .

I have now managed to move many of the files by doing
the following:
- run fdisk, label and newfs under 8.0
- reboot to 7.2, mount, place files on device
- reboot to 8, files now in place

Some further observations:
- many of my devices, including single-partition devices
   constructed using:
 	 fdisk -I /dev/XXX
 	 bsdlabel -w /dev/XXXs1
 	 newfs /dev/XXXs1a
   are not available from 8.0 if constructed under 7.2,
   however I can get things to work the other way around.

- when I re-setup the disk (using the same commands as
   above), I am consistently getting the "benign" warning
   "geom not found", which never appeared under 7.2

Any thoughts?  It is quite a pain to dump/restore whole
external file systems simply to set up an apparently-identical
replacement.

Does anyone know much about the recent filesystem changes?
Is there a doc somewhere that outlines these?

Andrew.