> As far as I know
> this shouldn't make a difference but, when I entered sd2b this time it
> progressed a little further but with a new error. Now it complains
> that:
> 
> root file system type: ffs
> stop: parity error

 Hm. The partition seems to be recognized correctly but stops booting.
You may try to re-write the miniroot.fs again. During your tries using
other partitions as root, you have destroyed the contents of the swap
partition (the dump partition).

-- 
Markus Illenseer