Is TimeMachine recomended to backup an HD or are others better for the job. It's not for me. Can it be set to overwrite old files and not to keep everything? Yes, it works well for its intended purpose. No, it is not for everyone or every situation. No, it can't be set to overwrite old files on anything but its own timeframe. There are still other choices: Carbon Copy Cloner and Retrospect, to name two (I'm sure there are more). I use Time Machine on my main disk. I also use CCC to do a second, offsite backup and to back up data on other disks. Craig