I have a 56 TB local Unraid NAS that is parity protected against single drive failure, and while I think a single drive failing and being parity recovered covers data loss 95% of the time, I’m always concerned about two drives failing or a site-/system-wide disaster that takes out the whole NAS.
For other larger local hosters who are smarter and more prepared, what do you do? Do you sync it off site? How do you deal with cost and bandwidth needs if so? What other backup strategies do you use?
(Sorry if this standard scenario has been discussed - searching didn’t turn up anything.)


Personally I deal with it by prioritizing the data.
I have about the same total size Unraid NAS as you, but the vast majority is downloaded or ripped media that would be annoying to replace, but not disastrous.
My personal photos, videos and other documents which are irreplaceable only make up a few TB, which is pretty managable to maintain true local and cloud backups of.
Not sure if that helps at all in your situation.