That's cool. BTW, I'm just wondering...

Would a system crash while doing a (mirrowed) dump
corrupt both disks at the same time?

While I was trying to use a couple of ide disks to
survive disk crashes, I thought it would be better
not to use a real mirror because a crash at a bad
moment could perhaps leave the cached worm unusable.
(I had a crash while doing a dump on a cached worm and
 the cached worm became unusable).

Am I missing something? A recover procedure I don't
know of? Or perhaps some code in the mirror device tries
to deal with that?

Another question I have is can you rebuild your mirror
device just by raw copying of one disk into another?