> That violates the 3-2-1 backup rule.
Ehh? Not really. All of these things we're talking about are components of our backup strategy.
If I wanted an offsite backup, its just rsync to some cloud provider (like rsync.net) or something. I don't do that because I don't think my data is worth the recurring cost of that, but its an option.
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My point is that when my solution is 200MB/s and on the order of $500 to $1000 for the component ($500 if you build your own NAS, $1000 if you buy premade parts. Assuming 2x 5TB hard drive is just $300 for 5TBs of _mirrored_ storage)...
While your proposed component costs $30 per 0.1TB and read/writes at a lousy 70MB/s... to get the equivalent mirrored setup you need to buy 100 Blu-Rays or roughly $3000 in Blu Ray XLs alone (2 copies of your data across 2-different Blu Rays, for the same redundancy factor as the 2x Hard Drive solution).
So I have to raise my eyebrows a little bit. How are you checking that the data doesn't degrade? Are you manually checking all of those BluRays you've created for reliability? That's a lot of sitting around and inserting / removing drives.
Its literally cheaper to build a 2nd NAS and stick more hard drives into it, and keep that 2nd NAS offsite somewhere.
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If you're gonna hold my feet to the fire over this "2-media" thing, then my 2nd media of choice would be Flash storage before Optical. Because SPEED is king. Speed means you can checksum your data and ensure that your backups are still good. I think Flash is a bit expensive compared to HDD, but based off of these BL-XL disks, I'm thinking that Flash is actually cheaper than Blu Ray and something like 10,000% faster. (Tapes would be a more ideal 2nd media... but I'm not "big enough" to make tapes cost-effective).
Yes, checksums and scrubbing. If you want to protect against bitrot (in ANY medium), you MUST double-check your backups over time.
TEST your backups. Any backup strategy that doesn't have a regular testing schedule is null-and-void in my opinion.
I seem to think that HDD, then Flash, and MAYBE Tape (if you're going really, really big) are the mediums of choice of the modern computer user. I'm not really seeing where Optical fits in today's world. Maybe a future Disk format (with maybe TB-level disks) can make Optical a thing again... but 100GB Blu Rays aren't really in the works for the modern user.
70MB/s is slow. And 100GB is too small per storage unit.