If you all you care about is TB/$ you still cannot beat tape as long as you are using enough tapes.
It really depends how much you are talking about
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If you all you care about is TB/$ you still cannot beat tape as long as you are using enough tapes.
It really depends how much you are talking about
Tape is cheap but very sensitive. They absolutely need dark places with stable temperature and humidity.
I sugest you either grab a few HDDs that'll last 3 - 8 years on average or pick SSDs. SSDs are expensive but very robust. You can exect a livespan of over 10 years while manhandling them. Both HDDs and SSDs nerd to be plugged in regulary to refresh the magnetic fields that contains your data - at least once per year. That means you have to copy everything to make sure it's refreshed.
No matter what you pick you'll nerd a strategy against bit rot. That usually involves at least 3 copies of your data. The hashes of said data of each copy are compared. If one hash doesn't match the other 2 that copy will be deleted and restored from one of the other copies.
Magnetic media are still the best for offline backup. A good tape drive, or hard drives if tape is not your cup of tea. If you don't want a NAS, you can get a hot-swap SATA drive bay that allows plugging one drive into your computer at a time.
Recordable optical discs are a bit of a gamble for long term storage. Sometimes they last for ages, and sometimes they don't. There are some made for "archival" purposes, but those are generally expensive and as far as I know not exactly well proven. Another drawback is that you need a lot of discs, all of which will eventually become plastic waste.
Don't use flash drives for offline backup. Their charge decays when left unpowered, and your data with it.
Whatever medium you choose, be sure to make more than one copy, in case one of them fails.
I also have dvds that I use as storage sometimes. There are also m.2 nvme ssds and even USB drives that you can find for cheap. I still have many memory storage that I've had for a while. I'm not exactly sure if you are planning on having this storage always accessible, but I don't see an issue with DVDs. You can still fit a lot on 4 GB DVD and if you need something bigger there are a lot of cheap SanDisk generic USB drives you can get at like a Walmart.