I did a complete back up of all of my hard drives due to the games computers love to play, especially mine. It took 3 days, 12 hours, and 54 minutes to back up in a mirror copy all of the data I had on the three drives. I never turned the computer off and barely touched it during this time for fear of screwing something up and having to start from scratch. There are 44 sub-directories. Peace of mind at last.