Question: I am backing up 600MB of MP3 files or other compressed files using maximum compression but the back up size increases to 650MB instead of getting smaller, why? Answer: Since compressed files (AVI, MP3, JPG, GIF, DIXV, ect.) are usually as compressed as they can get; using compression on compressed files will actually increase the size due to the overhead of the compression program. When backing up mostly compressed files it is recommend to set our program to "No Compression" to save space..