It is possible to someone knows what i had on a hard-disk even it was formated?

Question

What software can do that in case the answer is yes?
Same question for low-level format.

Answer 1

Yes!

To Completely Wipe your Hard-drive clean use the following.
Recommended by the University of Harvard Computer Science Division.

"Darik's Boot and Nuke (CDR/CDRW Version) - [2006-03-19 | Freeware | 1.9 Mb | DOS | 7914 | 4.87 ]
Securely wipes the hard disks of most computers."

The direct link is currently at:
http://dban.sourceforge.net/

USE EXTREME CAUTION and label this disk! Only insert in a PC you want to wipe clean of ALL DATA!

NOTE:
Most Hard-drives are shielded from external magnetism so unless you crack open the case and rub an extremely powerful magnet on the disk, that wont do any good. Floppy disks are unshielded and you can erase them with a magnet, but not a shielded Hard-drive.

Re-Formatting your Hard-drive will NOT erase any information. it only clears the FAT File Allocation Table, it does not erase ANY files as most people think.
Give me a hard-drive that has just been formatted and I can get EVERYTHING off it and copy to a NEW drive with NO PROBLEM at all.

Answer 2

Formatting a hard drive is like removing the card catalogs from a library, but leaving all the books on the shelf. Although the card catalogs has been removed, that tells where all the books are, anyone can still simply walk to the bookshelf and pull a book off and read it.

If there are just files here and there that you want to securely delete (shred) then there are programs that do that. I used SpyBot as my anti-spyware, and that has a built in secure file shredder (you can also specify how many times you want it to be shredded).

Answer 3

the only way to erase a disk permanentaly is to destroy it.data on a disk is never erased .Only the pointers to the data are removed the information remains.You can over write a disk as much as you want and with the proper micro tools you can retrieve bits and pieces of personal data .This is what the FBI do when they seize your computer

Answer 4

Absolutely, even if the entire disk has been overwritten 3 times you can still tell what was on it. I think that there is a product called disk eraser.?.