Imo the tapes are best long term storage medium. You can easly get around 25 years of storage from a tape. Unfortunately streamers are expensive and hard to use. I always toyed about buying a streamer for my data... Ended up hoarding HDDs...
But if we speak about 100s of years.. Hmmm, unsolved stuff..
For hard drives that are powered off for a long time "stiction" is a real concern. Yes I know, parked heads and all that, but powered off HDs for many years with varying temps/humidity gives my nether region a pucker thinking of the data loss
Yeah.. I store them at home, so temp is 23-28 deg. Usually in those plastic little boxes there were sold in. I know they will eventually fail. I just do NOT have cheap reliable option to store backups. Those disks are leftover of upgrades, like.. 20GB, 120GB, 320GB, 1TB :)
Some are reused in cheap USB ext cases that have IDE/SATA connectors.
But if we speak about 100s of years.. Hmmm, unsolved stuff..
I have a complicated relationship with LTO, QIC and QIC mini. Mostly it works but it senses fear like printers …