[wccrawford]

If redundancy was cheap and easy, we'd do it even if we had reliable data centers.

It's not, and that's why we don't have it.

[mbreese]

And therein lies the argument... that it would be cheaper to building in data-center redundancy into your design that it would be to ensure that your data center had 5-nines of uptime.

And if you're large enough to require 5-nines (or even 4) of uptime, you should be looking at data-center level redundancy anyway.