incorrect super block

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

I'm updating a box from 7.99.6/amd64 to 7.99.20, so kernel is .20,
userland .6.  I'm puzzled by:

# raidctl -s raid2
Components:
           /dev/wd1f: optimal
           /dev/wd0f: optimal
,,,
# disklabel -rt raid2
raid2|Automatically generated label:\
        :dt=RAID:se#512:ns#128:nt#8:sc#1024:nc#192533:\
        :su#197154432:\
        :pa#197154432:oa#0:ta=4.2BSD:ba#0:fa#0:\
        :pd#197154432:od#0:
# fsck -f /home
** /dev/rraid2a
** File system is already clean
** Last Mounted on /home
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
771 files, 67335 used, 48451404 free (140 frags, 6056408 blocks, 0.0% fragmentation)
# mount /home
mount_ffs: /dev/raid2a on /home: incorrect super block

Either mount is confused, or fsck missed something?

Cheers,

Patrick