Phil
Yeah, you almost got it. What I was advocating is less complexity (and cost) ... I am still not a fan of RAID (although, in response to my last time uttering this feeling, a forum user (
fordem) -- correctly -- reminded me and everyone of the benefits). Your 1 TB array is hard to "Mirror" (which is what RAID-1 does), unless you have an identical setup, and is best done in hardware (which adds more cost). Your original proposal (and the questions that go along with it) is, however, definitely the ideal solution (0+1). And if NASLite can do that, go ahead. I was interested in finding out whether it is possible to use a single disk (would have to be 1TB in your case, but I was thinking of mirroring a 2x250 RAID-0 array with a single non-RAIDed 500GB) and the built-in mirror function. You are correct, unless you are doing real-time RAID-1 you could lose the last 24 hours worth of changes, but I think of NAS more as a warehouse of infrequently changing data.
Enough of the theory though ... what
I actually do is to have a second server that mirrors the critical disk on my main server using NASLite's built-in rsync. (The second server only runs 1 hour per day, automatically woken up and shutdown from a WinXP system via TaskManager.)
You are correct, RAID-0 for speed (but then you should also invest in Gigabit NIC) and RAID-1 for safety. Hope the "tech heads" can answer your questions (and mine) ...

Georg