external hard disk copying internal hard disk

[fabujin]

I have an external Hard disk LaCie 500Gb plugged by USB to my Mac G5 which holds an internal hard disk of 230Gb
I noticed that whatever I do on the internal hard disk, it goes also on my external hard disk and if I delete some files from the external disk, it also delete the ones on the internal hard disk too.
I haven't set up the backing system on my Mac yet so I am wondering how this can happen.
What I want to do is make the external hard disk independant from the internal one. How can I do that?
Thanks for your suggestions!

[Buzz]

It can't happen.

You must have something in place running backups. Or you are not looking at the disk contents properly.

There's no way removing a file from a hard drive would cause ANY file on ANY other hard drive to be removed.

[fabujin]

well,
what I've just done now is delete a file I had on my LaCie external drive and put it in the trash. Then, when I looked at my internat drive, the exact same file has been deleted too! So if I had emptied my trash, I would have completely lost the file.
Which is the problem, I want to delete files on the external drive to empty it and start from scratch with building a backup of the internal drive on this external drive.
So I would like to know how to avoid affecting the files on the internal drive while I am deleting files on the external drive.
Hope it's clear!

[Buzz]

What you are describing defies the laws of physics and is not possible.

Disconnect the external drive. Are your files still on the internal drive?

[fabujin]

I've disconnected my external hard disk and actually 1 file, which holds all my images and which I used often, as dissappeared from the internat hard disk.
The file name is listed on the external hard disk with a little bended arrow on the bottom left of the file icon.
Does that arrow means my files will always being transfer to the external disk whatever I do on the internal disk?
How can I remove this arrow which I believe means my files will be transfered to the external disk?
I want the external disk to be used as a back up but not to prevent my files not to be recorded on the internal disk.

[Buzz]

The arrow means it's an alias, or symbolic link, or shortcut.. which ever term sounds familiar to you.

WHat Aliases do... is look like a folder but they are just reference points. Anything you drag to the alias you are actually dragging to the original folder, in this case, it sounds like the original folder is on the external hard drive and you merely have an alias on the internal drive.

To have the same content in both locations do this....
Go to the folder with the little arrow on it. Put it in the trash (don't worry it's just an alias and doesn't actually contain anything.) If you're scared to do trash it.. just move it to the desktop for now.

Now, plug in the external drive. Find the original folder, click and drag that folder to the internal hard drive. The copying dialog should pop up. Let it copy.

You will then have copies on both the external drive and internal drive.

You can trash that alias at any point, you can always make another one by highlighting a folder and then choosing File > Make Alias from the Finder's menu.