I understand that the "c" partition is special. But when the entire disk
(i.e. wd0c) is just acting as a storage backend and the svnd device is
the front end, I don't think it matters. It's not like I'm going to be
running newfs or fsck on the actual disk. Anyway, I have tried on the
"a" partition too, but I get the same results.
Like I said, everything works fine if I use the buffered device,
wd0[ac], not rwd0[ac], but it is so slow. dd'ing to the unbuffered
device is much faster than dd'ing to the buffered. That is why I thought
I would try to associate the svnd device with the unbuffered disk device.