

Magnetic tape. It’s one of the better long-term offline backup solutions. It is compact, inexpensive, has no moving parts (bearings, motors, reader heads), no scratchable surfaces, and can last for decades in a moderately climate-controlled room.
Just keep it away from magnets… or iron vaults. According to an anecdote (that I can’t find right now), a large bank vault was repurposed as an offsite backup storage, except it kept wiping the magnetic tapes because the thick iron walls reacted to changes in the geomagnetic field.
Calling something “literall 1984” is trite, I know, but this is pretty damn close to getting charged with wrongthink.