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.)


I mean, if you want a full mirror, rolling your own backup target is going to be the cheapest option even with the current high price of hardware. Other options are cloud storage, or using another media like tape. Cloud storage is of course an on going cost which rules it out for me, not to mention privacy concerns. There are certain “cold storage” options from cloud storage hosts which are considerably cheaper but they have limitations on how the data can be accessed and how often. The tape route is possible but it’s not really viable for home use due to the high upfront cost of the drives. Outside of that, backing up a subset of your storage as others have suggested is the only other option. Creating viable backups without breaking the bank is a challenge as old as computers, unfortunately.