Not true, it provides EITHER linear append or RAID-0 striping (there's the
mirroring). I'm not sure what the Duplexing thing is, however..
I've only heard the term "duplexing" in the context of Netware. Netware seems
to differentiate between mirroring where there are two disks but only a single
controller, versus duplexing where there the two disks must be on separate
controllers. In the rest of the literature I've seen, it's pretty much assumed
that mirroring implies separate controllers or at least separate channels.
Given that SCSI controllers for software RAID are generally far cheaper than
the cost of doubling the number of disks, I don't see much point on skimping
and allowing the controller to be a single point of failure.
Leonard