I have used time machine backup before, but I'm confused by what it really is doing. it says it will copy the whole disc at first, which can take a n hour or more, i understand, and then it says every hour when it is active it backs up tthe current state, and does so by copying only the files that have been added since. the last backup. Ok that makes sense. What about if i delete some fiiles ? Are they deleted from the current back up some how? How can it save deleted files information? does it save a record of the folder contents n some kind of list snf then not include the deleted ones, but that is not what appears on the external drive. It appears to have many copies of the whole kit and kaboodle, They aren't aliases of the files or at least they don't register as aliases. But that must be what itis . The previous versions of the backups from every hour back through the 1 hour intervals appear to be the whole backup. i had a smaller ext hd once for this and when Timemachine reached the capacity of the disc, without any warning at all, it automatically erased the oldest backup! so I shut it down instantly. here's the issue if you have not guessed. I deleted files to make room on my computer's internal drive, routinely, because i was secure iin the knowledge that Time machine had already backed up those files adn i could get them back any time. Then Time machine began to erase older versions of the hard drive , effectively losing my files i deleted specifiacally because they were backed up! suck!.In this case time machine did the exac opposite of what it is for.