Hi, I have been using Time Machine for about a year now and it works great but I was wondering what TM does when my hard drive gets full. I believe it deletes old files, but what if those old files have been backed up only once, are they going to be deleted? Other question, why is that my external HD, the one Im using for TM has three times more used space than what my local HD has? Does that means that TM has backed my stuff three time, I thought it only backs up the files that have been change?. Thanks a lot for your help.