I have a system in place where I back up my work files daily to a portable hard drive. I actually have two portable hard drives - one is stored off-site and I swap them regularly.

I also keep my family photos and other historical files backed up, but I only back the photos up occasionally (ie when I have new photos).

The backup media is for backup only, and it is unlikely I will ever read the files from the backup media unless a disaster occurs and I lose the master.

It worries me that my backed up files could become corrupt without me knowing it. It is also feasible that my master files could become corrupt, and eventually the corrupt files would be replicated to the backup media.

I'm currently using Cobian Backup, but I'm open to alternatives.

Is there a tool I can use to confirm that the backed up files are identical to the files that were first copied? I know it would be possible to generate a checksum and periodically validate the backup files against the original checksum, but I'm looking for a tool which will do this automatically.