The Night Shift

There's a great write-up by Brian Crescimanno called Why Are You Still Deploying Overnight? which I really enjoyed.  There's a lot of good logic there, but I think there's one missing element, and that's hardware (my favorite).  If you're going to flip a switch and watch your new software take over from your old software, you're going to need adequate hardware (or hardware + virtual machines) to allow yourself to switch back.  If you're not allowing yourself to switch back, you're betting on very fast problem resolution, presumably done by very clever engineers.  This is a better plan at, say, 9:00 AM than 3:00 AM, but it's still more dependent on heroics than software/hardware quality assurance.