Not exactly what you're asking for, but I think worth considering: LTO-6 data tapes.
I have about 29TB of blu-ray rips that I didn't want to risk having to re-rip (that took months!). My solution was to buy an LTO-6 tape drive on eBay, and about 100 tapes.
If you get lucky, a used LTO-6 tape drive will cost you roughly $250-$350 on ebay. The tapes themselves can be had for about $10 each, particularly if you buy a lot at once. Each tape can hold around 2TB [1]. I have all my movies backed up twice, on two tapes each. I have a label maker where I label the tapes from A-Z and I have a spreadsheet keeping track of which movies live on which tape, in case I need to restore just one.
I don't know if there are any kind of proprietary blobs in the kernel required for this, but I was able to get this working on vanilla NixOS with the `sg` kernel module enabled, and the open source LTFS implementation from HP [2].
The tapes are actually a lot faster to read and write than people think, but you can only read and write one file at a time, so you have to plan accordingly. They're also not random-access, so even though LTFS gives you a filesystem mountpoint, you probably don't want to be rsyncing files directly to them. It's not a "RAID", just a regular filesystem so when I run out of tapes, I can simply buy some more.
I keep them in a big plastic storage bin, and I have a ton of desiccant in there to protect against humidity. I haven't lost any tapes yet, and they're rated for like 15-30 years, but I want to hedge my bets a bit and desiccant is not expensive or hard to get.
Still, I am very happy with my setup. It's saved me a lot of time after I broke a RAID configuration and lost all my blu-ray rips for my Jellyfin server.
[1] They advertise like 6.5TB but that's sort of a lie; that's assuming the best-case scenario with their on-board compression. If you're backing up already-compressed stuff like video or photos, you get much closer to the 2.5TB limit, and you don't really want to run them to the edge I think, so I stop after 2TB.
In regards to "testing", I didn't do anything too elaborate. I filled up a tape with movies, then copied them back, and compared the md5sum of each of the movies to make sure nothing had changed. They hadn't changed so I was happy enough with the results.
Also, I forgot to mention, most of the tape decks I've seen are SAS-only, so you'll either need to make sure your computer/server/whatever has a SAS port, or you'll need to find a card that has one. I think the modern LTOs have thunderbolt support, but I haven't used them. I simply found a used PCIe SAS adapter on ebay for $35 with shipping, and plugged that into my server. I think the only things I had to directly install were `mt`, `ltfs`, and enable `sg`.
Ever since watching the robo-tape floor at a company where I did an internship, I have been fascinated by high density tapes. I probably won't do this but I like the suggestion.
I think it's definitely worth considering. I was using Google's cold storage backup for my blu-rays for awhile, which was great until I needed to do a total restore from backup and it ended up costing me almost $800! Be careful with cloud computing if its your wallet on the line.
It was a bit of an upfront investment to buy all the gear, but I can restore from backup as often as I want for free, and my total cost for gear was less than $800 so it was fairly easy to justify.
I would really like to get one an LTO-9 drive, at some point, but they are way too expensive for me to be able to justify right now, even used. The tapes themselves can be had fairly reasonably but the drives (particularly the external ones) cost like $4000+, even used. In fact that's true of basically any LTO standard after 6. Once the thunderbolt drives get down to less than a grand I'll probably pick one up, but I suspect they're expensive because they're not really marketed to "consumers", but instead to entities where "cost is not an object".
I have about 29TB of blu-ray rips that I didn't want to risk having to re-rip (that took months!). My solution was to buy an LTO-6 tape drive on eBay, and about 100 tapes.
If you get lucky, a used LTO-6 tape drive will cost you roughly $250-$350 on ebay. The tapes themselves can be had for about $10 each, particularly if you buy a lot at once. Each tape can hold around 2TB [1]. I have all my movies backed up twice, on two tapes each. I have a label maker where I label the tapes from A-Z and I have a spreadsheet keeping track of which movies live on which tape, in case I need to restore just one.
I don't know if there are any kind of proprietary blobs in the kernel required for this, but I was able to get this working on vanilla NixOS with the `sg` kernel module enabled, and the open source LTFS implementation from HP [2].
The tapes are actually a lot faster to read and write than people think, but you can only read and write one file at a time, so you have to plan accordingly. They're also not random-access, so even though LTFS gives you a filesystem mountpoint, you probably don't want to be rsyncing files directly to them. It's not a "RAID", just a regular filesystem so when I run out of tapes, I can simply buy some more.
I keep them in a big plastic storage bin, and I have a ton of desiccant in there to protect against humidity. I haven't lost any tapes yet, and they're rated for like 15-30 years, but I want to hedge my bets a bit and desiccant is not expensive or hard to get.
Still, I am very happy with my setup. It's saved me a lot of time after I broke a RAID configuration and lost all my blu-ray rips for my Jellyfin server.
[1] They advertise like 6.5TB but that's sort of a lie; that's assuming the best-case scenario with their on-board compression. If you're backing up already-compressed stuff like video or photos, you get much closer to the 2.5TB limit, and you don't really want to run them to the edge I think, so I stop after 2TB.
[2] https://buy.hpe.com/us/en/storage/storage-software/storage-d...
ETA:
In regards to "testing", I didn't do anything too elaborate. I filled up a tape with movies, then copied them back, and compared the md5sum of each of the movies to make sure nothing had changed. They hadn't changed so I was happy enough with the results.
Also, I forgot to mention, most of the tape decks I've seen are SAS-only, so you'll either need to make sure your computer/server/whatever has a SAS port, or you'll need to find a card that has one. I think the modern LTOs have thunderbolt support, but I haven't used them. I simply found a used PCIe SAS adapter on ebay for $35 with shipping, and plugged that into my server. I think the only things I had to directly install were `mt`, `ltfs`, and enable `sg`.