> In any case if you need reliable optical backups you should be testing the burn quality. Many don’t do this, but then how do you know the disc has sufficient

> In any case if you need reliable optical backups you should be testing the burn quality. Many don’t do this, but then how do you know the disc has sufficient signal margin? I've got some original and new Verbatim M-DISCs that I burned full with a few hashes. Every now and then I leave them in the patio for a few weeks but they often get used as coasters in my office. When it gets time to test I rinse them in the sink with soap and water and dry them with the kitchen towel. I test them every few quarters. So far they've lasted a decade and haven't lost a bit. One of them has some slow spots but so far they're all perfectly fine. Good luck storing a hard drive through thunderstorms and in 100F days in the sun for a decade and reading the data off them. I'm not too worried about their durability. And since it's $10 or less for a replica I can make a few and still not spend a ton. And sure, that 20TB drive is $280. For redundancy I'll need to buy at least two. But I've only got maybe a terabyte or two I actually care about, so per terabyte it's a terrible price especially after buying 2-3. And then when syncing new stuff I'd need to move the drives around as I'm talking offline archives. Kind of a pain to go copy all the data at a relative's place hundreds of miles away, I'd need them to plug it in. Otherwise they can just stash the discs in a box for me when I mail them every quarter or so.