Quick question about back-up using Time Machine

Hi folks,

I have a quick question regarding back-up using Time Machine.

I bought an external hard drive and I synced it using Time Machine.
So I suppose all my musics and movies are in the external hard drive.

My question is, if it's okay now to erase all the movies i have in my mac.
(I think that's the point of back-up and having an external hard drive but I'm new to this process and want to make sure if I'm doing it right)

Okay, so suppose I erased all my movies in the laptop after the first back-up. A month later, I want to back up again; connect the external hard drive (which has all my movies in it from the back-up a month ago) and back up using Time Machine.

What happen to the movies in the hard drive then?

You know what my question is? Makes me confused too... lol

Thanks!

Anyone? Please?

I'm sorry to tell you this is not the correct way of using Time Machine and you could lose your data permanently doing it the way you are. TM does sync your computer with the external hard drive but unlike most syncing it will keep your old synced files for awhile. A true sync means that it will be an exact copy of your computer meaning that anything you delete will also be deleted on the external.

What TM does is a delayed deletion of your files which were deleted off your computer. TM will only keep old files until your external is full and then it will start deleting the oldest files first and so on to make room for new files. The larger your external hard drive is the longer it will keep older files but it's not a good idea to get into the habit of thinking that you can restore everything you have deleted. Unless you are constantly keeping track of what is deleted you won't know what files you still have left on your TM. A lot of people make the same mistake as you do about TM.

Also if you have only one copy of your files then you really don't have a backup. Deleting files from your computer and then having only a copy on your external hard drive means that you still have only one copy so you don't have a backup of it. All you did was transfer the location of your files for storage rather than make a backup copy of it.

If you want to delete files off your computer and then store them on an external hard drive you should get another hard drive and just manually drag and drop the files over using Finder. You then have to backup that data because you only have one copy once you delete it off your computer. You can either do this by getting another hard drive and syncing the two or use DVDs and make a copy that way. If you are curious I have several external hard drives because I have a lot of data. One is used for TM while all the others are used for storage and backup.

Whereas i have a Time Capsule which does the Historic backups as endlessmac states and as well i have 2 HDs that i rotate with a Superduper backup, one of which is kept off site. If i have a mechanical failure/Fire/Theft then as long as i have access to another Mac i can boot off Superduper backup and continue working.