I read many posts talking about importance of having multiple copies. but the problem is, even if you have multiple copies, how do you make sure that EVERY FILE in each copy is good. For instance, imagine you want to view a photo taken a few years ago, when you checkout copy 1 of your backup, you find it already corrupted. Then you turn to copy 2/3, find this photo is good. OK you happily discard copy 1 of backup and keep 2/3. Next day you want to view another photo 2, and find that photo 2 in backup copy 2 is dead but good in copy 3, so you keep copy 3, discard copy 3. Now some day you find something is wrong in copy 3, and you no longer have any copies with everything intact.
Someone may say, when we find that some files for copy 1 are dead, we make a new copy 4 from copy 2 (or 3), but problem is, there are already dead files in this copy 2, so this new copy would not solve the issue above.
Just wonder how do you guys deal with this issue? Any idea would be appreciated.
Checksums.
Personally, I use TeraCopy to safely copy a folder/file from my main drive to my backups (there’s even an option on there that will save a checksum of said folder/file on the backup so that I can later run that checksum and see if anything has corrupted).
What do I do if there’s corruption? Simply delete the corrupted files and replace them with good copies from other backups.