I'll just add at my current place with clustered Windows 2008 back-end, with AD and DFS, and distributed flash based , fan-less, Windows 7 embedded clients we've had zero down time in 8 years or so since it was implemented. End-Nodes provide serial data from the DFS shares to the machines. I'll grant you that is certainly easier than redundant real time control issues, a little bit. But. It's just all about planning for sure, on the software, hardware, and IT infrastructure end of it.
