Comment by shiroiushi

>Wouldn't it be more like $0.07/GB for BDXL?

Whoops, thanks for pointing out the math error; I've fixed it.

>If one got particularly lucky with HDD failure rates perhaps they'd survive running that long in RAID but one would expect some replacements over such a long period.

I don't think so: I'm not talking about keeping these drives spinning for 50 years, but rather in cold storage, just as we'd do with the BDXL discs.

>Some other things to consider are at high capacities all HDDs use helium now, which slowly leaks (WD/HGST have a SMART stat about the level*) and the cost of running drives/associated computers/maintenance over a long span vs the up front cost of passive writable media.

Helium leakage is an issue I didn't think of, and I don't know how sitting in cold storage for 50 years would affect this. But again, the costs of running drives/maintenance/etc. should be zero, because I'm comparing apples to apples. No one would seriously propose a massive array of BDXL drives with BDXL discs continuously available, so likewise I'm proposing just keeping 10+TB HDDs in cold storage.