I've checked out NAS solutions with mirroring via RAID, but found too many reports of complete data loss (due to failing box, controller) online to consider them secure. Given all the media center apps they come with I'm also questioning whether I'm even in their target market. Also there is the theoretical problem of ransomware wiping the thing.
Is tape manageable for private use, and are there any go-to solutions?
What about cloud storage with too-big-to-fail companies (S3 buckets)? It sounds good to have access from everywhere without carrying some box around. It is not needed to keep the data private but I'd prefer it.
https://aws.amazon.com/s3/storage-classes/glacier/
helps with the pricing (about $1 per TB×month The one problem you have is that you have to make sure the bill gets paid.
Another option is optical disks. A blu-ray drive is about $60. See
https://www.networkworld.com/article/3638116/why-aren-t-opti...
and
https://en.wikipedia.org/wiki/Optical_media_preservation
I've recently read CDs I burned in the 1990s and DVDs in the early 2000s. I've seen discs other people burn (particularly Chinese) sometimes get "rot" (dark spots) within months but I haven't had it happen to discs I burn.
LTO tape has taken over
https://en.wikipedia.org/wiki/Linear_Tape-Open
the drives for the newest standard are always crazy expensive, but you can get drives for an old version of LTO for less on Ebay. Tapes are available and affordable in terms of $/TB so long as there isn't a patent war between tape manufacturers.