Agreed, the HQ of my company has 2 generators on site, 1 near the building and another one on campus several buildings away. The first one is a diesel one that turns on pretty quickly to be able to catch the servers before they run around of power on battery backup. The second affects some of our other buildings.
Still, we could keep our servers running through a blackout(and have, a few years ago we had constant rolling blackouts, and had to rely on it quite a bit). While I'm sure SE has a system like that, I imagine staying up on fuel based generators would be pretty expensive, as iirc, Japan's fuel costs are almost double ours. (This site shows it at $5.19/gal last year)
