How does bitrot protection actually work?

I'd like to know too. I currently run checksums on all my files, and store the results. Periodically I recalc the checksums, and compare against the stored checksum. This at least tells me there's been bit corruption. The next trick is to restore a good copy. You know you have a good copy when the copy matches the original checksum. What you don't want to have done is backed up the rotted file, and all you have left is that rotted file. ReadyNAS has a versioning backup feature. So as time goes on, and bits are changed, ReadyNAS probably has multiple backups of both the good and bad file. So I'm guessing ReadyNAS either prevented that from happening in the first place, or is able to locate the good file (by comparing checksums).

This is a pretty important topic for me. I'm concerned a lot about silent errors.

It would be great if Netgear would do a good write up demonstrating some scenarios. I don't need to understand how, but I need to see the scenario proven. For example, use a hex editor and change the file (but keep the file size/date the same). ReadyNAS should detect the change, and should restore the file. The other scenario is the reverse...what happens when the stored checksum is corrupted?

Jake