The interesting thing is that for long term high reliable cold storage (for e.g. research data) using a bunch of tape robots seems to still be quite viable idea. (The robots read, check and replace broken tapes automatically getting data from tapes can take long so you normally put some form of sdd cache in front of it.)

Then you place the tape robots into a fireproofed room with exhaustive protection measurements (e.g. filling the whole room with CO2 or similar on fire alarm, having extra fireproofed doors which are comparable with bomb shelter doors etc.).