Also, don’t forget paper exists. For smaller documents, it could be worth printing them, and putting them in a water/fire resistant safe.

Before paper, and somewhere in-between the digital and analogue, maybe go weird with discs or magnetic tape drives (if you're really into your electromagnetic data storage)?

And for the sillier side to this: don't forget to laser etch the most important records in stone. Don't think it's worth the trouble? Wouldn't have some of our ancient records if they weren't literally carved in stone, so...Incidentally, would anyone happen to know of any personal robotic stone engraving tools one could get?

Would be fun to pass in some text and let a machine go to work on some stray stones.