Well, at that point, why not LTO? Much better price-per-TB, despite initially comparatively expensive buy-in price for the drive/library.

If you're not an enterprise user, LTO makes no financial sense whatsoever. In addition, it just isn't very convenient; it's not a random-access media. With a HDD, you can just plug it in, use rsync to update only things that have changed, unplug it, and set it on a shelf. The use case is entirely different.

SSDs are useless for offline storage: if they aren't powered on and accessed often enough, the data just disappears. They're totally unsuitable for archiving.

On a tangent: are there any data about nand data retention in low temperatures? Such as putting microsd in a freezer at -15°C ?

Whaaa? How much time? Does this also apply to SD cards and such?

Here's a link I found with a quick google search: https://www.minitool.com/partition-disk/what-happens-to-data...

According to this, JEDEC Solid State Technology Association's standard is that SSDs should be able to retain data for 1 year at 30C. Not great for an archival medium.

Here's a Quora discussion about it: https://www.quora.com/How-long-can-SSD-store-data-without-po...

Vendors will claim much better numbers than this, but the standard isn't very good.

It is also not at all clear what is needed to "top up" an offline SSD to assure the data is maintained. Some people say that merely connecting the drive to power for a few minutes to hours lets it restore the fading bits but others think nothing but a full rewrite of the data will. I haven't seen any official information or testing on this either so the conservative rewrite assumption seems the most reasonable.

What's big in offline storage these days? I did some work for UPS in the 2000s, and they used giant tape reels. Is that still the norm?