Multitasking can lead to disastrous results!

That 40 page document you were working on while talking on the phone, downloading and reading your mail, checking the latest stock prices and looking out the window at the awesome girl in the short skirt ( ladies just insert Brad Pitt type guy here) ended in panic when you deleted the 40 page document and not the spam mail you thought you were deleting.... D' oh ! Not to worry, it's still in the trash ain 't it ? Uh oh in all that multitasking ( and drooling!) you emptied the trash.... it's gone forever :-(

Well not quite!

Let's think of a Hard Disk as something like a filing cabinet. It's got lot's of folders, each folder has a name on it and contains files within. You identify the folders because they have a name on them, so we got a Kitty folder, amongst many others. Within the Kitty folder is lot's of pretty neat Kitty Picks. What if you removed the name on the Kitty folder, so that it was now blank?

You ask someone to find the folder in the filing cabinet titled Kitty and they are not going to find it are they ? No, even though it's still there, someone following strict instructions to find a folder called Kitty is going to draw a blank. The folder and all it's contents is still there, but it's not going to be found. If you asked someone to find a folder which could be called anything or nothing, but contains Kitty pictures then their exists the possibility that the file would be found. When you delete a file on a computer it's still there, all you do is remove the "name" of the file, or the reference that the computer used to find that file. The file is still on the HD fully intact.

All that happens is that the computer say's "OK, I will remove the name of that file, and free up that block of space for future use". The file will remain intact until the HD uses that space to store another file, then and only then will it overwrite the original file. Now it's lost forever........

Eh, not quite!

Data is stored on a HD something like the lines on a road. You got a white dashed line down the middle of the road, they look pretty perfect as you drive down it, all straight and neat looking. What if you decided to change the colour of the white dashed line down the middle of the road to something else, say yellow. The guys would arrive along with their paint gear and over paint the white line to a yellow one. As you drive down the road all would look normal, a yellow painted dashed line. Get out of your car and take a close look, what do you see? Some specks of the original white paint will be there to be seen on either side of the now yellow line, its the over spray from the original line. And where there is no over spray to be seen from the original line, you could conclude that there was no white line there.

You could with a pretty good degree of accuracy re map the original white lines! Well a HD lay's it's information in a similar way, except rather than a spray or roller it uses magnetism. But like spray paint it has a degree of "overspill" , so like our spray can they will be magnetic particles left behind from the first file. Pretty neat huh ! Things are getting pretty expensive now,the girl in the short skirt is gone and your looking at a huge bill!!! This stuff is not for the ordinary Joe, rather the computer forensic guy. But with time and patience a skilled operator will get back something.

To thwart this their are applications that will "over spray" or overwrite a HD with tons of random one's and zero's many times, just like repainting the white lines many times over and over again and again till it's pretty impossible to find anything of value. Their is a MOD ( Ministry Of Defense) standard for this. But don't you know, it someone comes up with a way to obfuscate the data on a HD someone else is working on a way to recover it!

So to conclude - you delete a file, it's in the trash no panic. You empty the trash, sorta panic! Stop using the computer, using another computer download PC Inspector ( free) install it, remove the HD from the first computer and scan it from the second computer using PC Inspector. Your files should still be intact and recoverable.

Life is good again :-) Lastly, if your getting rid of your computer for a nice shiny new one, remove the HD and trash it to bits, good fun and your data is safe from prying eyes! Even if your passing it on, you ( or the new owner) can get a replacement HD pretty cheap. I know of people who buy second hand HD's on eBay just so they can scan them and retrieve information. There was a story on the net a short while back, a "well known" European TV presenter sold her Apple power book, the guy that bought it "found" a video of her that her mother would not want to see!!! Be careful out there :-)