Data Backup and Restore Corruption

[Biohack]

Hi everyone, have a question about backing up data. I'm worried about corruption of files when I copy files to an external drive and then restore them back to my new drives. I'm thinking I should hash the files and make two copies of them to two external drives then copy them back while checking that the signatures are unchanged. Any comments about this?

[tikker]

There are tools that allow you to verify the copy was successful by e.g. checking a hash after the file has transferred. I'd take a look at those if you want to be sure the files got transferred correctly. Additionally if you are really paranoid you could also store the hash itself somewhere and periodically check the hash of the file against that reference. I think there are also filesystems, like ZFS IIRC, that have means of helping you protect against corruption (but maybe ZFS is not that suitable for cold storage? I haven't used it personally).

[Kilrah]

I have my main storage that gets backed up to 2 external drives. That's done using FreeFileSync in normal fast date/time/size comparison mode.

But about twice a year I'll run it in "compare file contents" mode to see if any discrepancy has crept up. That's not happened yet.

 

So after you've copied everything you could do such a file content compare before wiping the original drive, then one again against the 2nd backup once you've copied things back...

[Biohack]

Thanks guys, researching this topic further! Won't be able to use ZFS because I'm on Windows.

[Biohack]

Boggles the mind why this isn’t discussed more. I have been worried about corruption of stored files for many years. I’ve lost enough files to know this is an actual issue. Just had no idea how to solve it!