This kind of thinking is how you end up in a newspaper article where you're in a building in new york babysitting a generator during a hurricane while everyone

This kind of thinking is how you end up in a newspaper article where you're in a building in new york babysitting a generator during a hurricane while everyone sane is serving from Atlanta now. You're doing it wrong. Plan to lose sites. If you plan to never lose a building, you're just setting yourself up for pain by optimizing for the wrong kind of redundancy.