The "Wipe Free Space" option fills up all of the "empty" space on your hard drive with random data. Say I have a 160GB hard drive (usable space 148GB), I am using 60.00GB of data. CCleaner will fill up the remaining 88GB with junk. By doing this it writes over files that were not securely deleted. I know that much. However, I have a question of my own, related to this topic, so I hope you don't mind if i piggyback off your question.
WIPE FREE SPACE TECHNICAL QUESTIONS.
How does the Wipe Free Space work? In more specific terms, I have two questions. If my information is incorrect, please let me know.
"When you have applied the secure deletetion setting to 7 Passes, (or other), does using the 'Wipe Free Space' option actually overwrite the empty disk space 7 times?"
"I have heard in the past from data recovery 'specialists' that by examining the platters of the drive, data that has been overwritten can be recovered. It keeps some sort of short term magnetic history. This is the reason for multi-pass erasing in the first place. I have also heard that a 160GB drive, while you only see 148GB inside of windows, there is a lot of free space (say another 4-40 GB) that can only be seen by the hard drive controller. When a hard drive notices a bad sector, it allocates sectors from the unused 'spare' space, and puts a block over the bad sector, so that it is not written again. This keeps a disk in Tip-Top shape, and hereby making it last longer with fewer errors. Does this mean that if a file with sensitive information is written to a sector that the drive deems bad, when it marks the bad sector, the file could still potentially be recovered? Since it has been moved to and unusable area of the disk, utilities such as CCleaner's 'Wipe Free Space' are not going to touch this sector. Is this correct? Should we worry about this?"
