> > on a slice (or partition) level, where with tapes it was the 
> > entire device locked out.
> 
> That's correct.  I've used the Sequent machines a while back, 
> and their
> lock manager had a proprietary protocol which they ran over the SCSI
> bus.  I'd love a similar type of thing for NetBSD...
> 

I wonder if there has been any work done to do IP over SCSI.  I have
a heartbeat system in my first release of NetBSD clustering, though no
lock manager.  It all is done with UDP datagrams over redundant networks

Sequent had chosen to use both SCSI and the NETWORK to send the
messages, which IMHO is a little paranoid.  And I think it buys a 
few more problems.  I think the rational was because of the networking
being streams based and there were a few cases where it was easy to
dry out the streams on temporary basis which would cause a false
cluster transition.  Since we don't have streams to content with,
I didn't really think too much about it when I was doing the heart
beat stuff.

It would be nice to have a universal transport protocol sort of 
like VI was supposed to be (and I guess won't). It's funny to see all
the talk about SAN's (Storage area networks) moving in the direction
of using an IP protocol because of distancing and routing.  

Andy