File size difference

I am backing up files from my mac but notice that the size on the WD Mirror is smaller than the original. For example 720.8MB original becomes 687.4 on the WD mirror. This file size difference occurs on both MVK and MP4 files. Is this normal or do I have a problem?

Hello,

Are you talking about a single file or the complete backup? If it’s the complete backup it could be that there are some system files that wont be backed up.

did you not look at the two scene shots? They are individual files.
RogerTerry

If you copy it back, does it “expand” again? Do all file types do it or just specific ones?

I would wonder if you’re just seeing differences in how the file systems work and how efficiently your large file is broken down for storage on the drive.