Does wiping free space on disk free any space?

Question

CCleaner has a feature for wiping free space on a disk. CCleaner's documentations says:

When you delete a file, Windows removes the reference to that file, but doesn't delete the actual data that made up the file on your hard drive.

and

For privacy and security reasons, you can set CCleaner to wipe the free areas of your hard disk so that deleted files can never be recovered.

So, my question is: Does wiping free space on a disk free any space on that disk? If it does, does overwriting many times free more space?

Solution 1

Does wiping free space on a disk free any space on that disk?

No. Wiping the freespace just cleans the unused blocks on your disk. It's simply for security reasons, otherwise data rescue software can still recover the files

Imagine a disk like a kind of notebook. When you write some information to the book you'll have to write the particulars about that piece of information in the table of contents (ToC) at the beginning (or end) so that you can quickly find which page you wrote on. When you want to clean the data you just clean the corresponding line in the ToC to say that the page is free and can be used to write other information, but you don't erase anything in that page until you really need more space. The same thing occurs in file systems

Solution 2

No, wiping free space on a disk does not free any space on that disk.

All that wiping does is write one big file that expands to fill up all the free disk space, then delete this file when the disk is full. The amount of "free space" stays exactly as before the operation.

The reason for this is that the operating system only deletes the pointer to the file's data when deleting the file, but does not overwrite the data itself.

Solution 3

The other answers are correct. It adds no value unless you are need to hide illegal or confidential activity.

If disposing of the drive, easier just to drill through it a few times to stop some one from taking your data.

I wrote a DOD compliant drive wipe utility many years ago. The way it works it is goes to each unused byte on the drive and stores all 0's, then all 1's then a random value, and does this multiple times to eradicate the magnetic signature.

Deleting files just removes them from the MFT, a directory of sorts of the files storage locations.

So, for disk space purposes, don't bother. If you have terrorist manuals and want to purge them, well.... I guess then you would use a wipe tool.

As the commenter said, be careful on an SSD. It's somewhat pointless to wipe it, and if you do you can bet you are now really shortening its life. SSD's have limited write capabilities. So much so, they have special chips to randomize the writes to avoid overuse of certain sectors. Consider it, even wearing of the disk.

Long story short, don't waste your time. Also, I really suggest avoiding most of the "Clean your Computer" utilities. They are just spam pieces of crap that don't help.

Like, "Clean your registry".. Don't. Its really pointless.

Just defrag your NON-SSD drive, and keep on trucking.

Comments

[Robert]

Don't wipe your disk if you use a SSD: Wiping means a lot of write operations which effectively degrades your SSD faster so that it will fail earlier. On SSDs with TRIM support deleting a file usually means that the content is also no longer available as the SSD has marked the sectors as free -> reading the sectors just gets you null bytes.

[Oak]

It's worth noting that using that wiping free space never was intended to create free space, but to wipe the already existing free space.

[meneldal]

For SSDs you have to delete files entirely because you need to put back zeroes before you can write again, but it's something the OS does for you. So no need to use something else.