Mgalindo13
:smack: Thanks for catching this. Yes, I do a defrag and definitely NOT compression. As cheap as disk space is these days I’ve never figured out why compression is even an option.
Regards
Testy
To wipe free space on C: you can just run cipher /w:c:[name of any directory in your root directory] from a command prompt. This overwrites the free space three times, with zeros, ones, and then with random bytes. I guess if three passes isn’t good enough you can do it again.
This is built into Windows (XP and 7), so it is free and simple. I am a bit surprised no-one has mentioned it yet. Is there some downside to doing it this way?
It seemed as if the OP was looking for a little more than free space wipe and a third party program like CCleaner can clear out cookies, temp files, browser histories and so on.
Also, on a large hard drive, cipher can be much slower than a third party app.
njtt
Thank you for this but I’m not sure I understand it. So, I issue a command to cipher a directory in the root directory and it overwrites all the free space? That sounds very effective.
Thank you
Testy
I’d never heard of using cipher to wipe free space. Cipher is intended to encrypt data.
Microsoft mentions the /w option here. Says it takes a long time to run.
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/cipher.mspx?mfr=true
I Learned something new today. 
Testy:
Yes, the syntax is a bit odd, and I don’t really know why you are supposed to give it the name of some random directory, but it works. The most crucial part is the /w parameter. That is what tells it to overwrite free space rather than encrypt your data.
aceplace57:
Isn’t any means of overwriting a lot of disk space going to take a long time to run? Can it really be sped up significantly? One way or another you have to write to every single unused byte of space on the disk. On modern disks, that is a lot of writes.
Cipher /w does give you a rudimentary display of how it is getting along, so if you do not really think you need three full layers of overwriting you can stop it soon after it begins its second (or its third) pass. Just use Cntl-C.
njtt
I wonder what it is enciphering with? Is it supposed to be an actual security measure that is handy for scrubbing disks? I took a look at the MS site but didn’t see anything on what kind of enciphering it was doing. Is it AES or some variant or just what? In any event, I got what I needed to do done using the CCleaner tools. Very good application.
Best regards
Testy
Things like this irk me on some levels. Part of this is people thing there is some magical free program that pop up everything you ever did, every password, everything you ever typed and that all of that data is stored in some “secret log file” that some uberleet haxxor is going to read and is going to end up owning your house a week later. CSI makes it look like anyone with 5 minutes and a little knowhow can easily do this.
It is not true.
Simply reformatting and reloading will pretty decisively smash most of your data from all but serious recovery attempts. Off the shelf recovery stuff might be able to get some things back but many of the files will be damaged and or missing pieces. Even then the basic paid stuff is gonna cost you $50 to find out.
Taking it up to places like Drivesavers they can pull ALOT of stuff from a drive like that but we are also talking thousands of dollars in fees and millions of dollars in equipment to do so with no guarentee you will get a specific file that you wanted back. This would not be cost effective for identity theft and such. Plans for our latest stealth fighter prototype, yeah, smash the drive. A few vacation pictures… not worth sweating over.
A basic free space eraser like mentioned above is going to pull everything into the realm of unlikely to be recovered even by forensic data recovery places.
Someplace like a bank where a server might have enoug data to commit identity theft on thousands…crush it…one person…not worth the effort. Phishing is 100x more effective against individuals and 1000x more cost effective.
I know that this is a fairly standard bit of Nerd Lore, but I truly doubt that this level of random overwriting is necessary for an ordinary user. Recovering data after a single overwrite already requires heroic and expensive efforts. Again, unless the OP has something to fear from the NSA, or there are trade secrets worth five or six figures currently on the hard drive, a single overwrite pass should be sufficient. Some kid who downloads a few hard drive recovery tools, hoping to find something interesting, isn’t going to recover anything from that.
ETA: Basically, what Drachillix said.
For when you REALLY need to get rid of the data.:eek: A previous customer of mine was seriously paranoid about this issue. They popped the platters out and dropped them into an acid bath. That was the Saudi government.
Regards
Testy