A minor point: a fire-proof safe is not absolutely heat-proof. Put one in a fire, and it will heat up inside. Better ones also tend to release water vapour into

A minor point: a fire-proof safe is not absolutely heat-proof. Put one in a fire, and it will heat up inside. Better ones also tend to release water vapour into the safe itself when heated (as a mechanism for keeping the internal temperature down and providing a positive pressure for keeping smoke, fire, and particulate out), which isn't great for hard drives either. I wouldn't rely on an on-premisis safe to prove any data integrity guarantees against anything but petty theft.