you would have to prepare a checksum for your backup at the time that you make it. Then you can run the same checksum operation when you take the backup medium out of storage. It would go something like this:
Prepare your backup for storage:
1 Make your backup.
2 Ensure that you are happy with it.
3 Obtain an MD5 checksum on the storage medium.
4 Write that checksum by hand on the storage medium.
Verify medium from storage:
1 Obtain an MD5 checksum on the data on the medium.
2 See if that MD5 checksum matches the one that was made at the time that the backup was done.
Here is how I would implement it.
Create the backup. Let’s use the following conditions. We are going to create a tar archive file on a disk partition mounted on /mnt/backup. The tar file will be named test.tar.
Code:
root> tar -c –verify -vf /mnt/backup/test.tar

Okay so I just executed that and it worked. The tar file was created and it was
verified. Now let’s create an MD5 checksum for this known good file.
Code:
root> md5sum /mnt/backup/test.tar
9888fdc35f1233a021d6f2c2e4ce5a6f /mnt/backup/test.tar

Now write that MD5 checksum onto the backup medium. When you retrieve the backup medium from storage you just run an MD5 checksum on the backup image and compare it to the one that is written on the medium.

via creating tar files with high data integrity.