Any idea how a 'shredder' works?

[Why Syzygy]

I've heard about changing all the 1s to 0s. Do they all work that way? I use Revo Uninstaller's "Evidence Remover". I could probably find info on their site. They have very good documentation. As it was running a bit ago, a system warning came up that it was running low on disk space. I have 75% free! I launched Defrag, and sure enough, it said -0- available. After I ended the cleaning (it was 99% finished), it reverted to the correct reading. There have been a few times when I run it that it goes BEYOND 100% completed. If it gets to 101-102%, I've always cancelled it. That scares me to see that.

Any idea what causes this weirdness?

[pokerfan]

1. Pretty much

The way they work is to rewrite the entire surface of the hard drive by first writing ones followed by zeros. In order to do this, the program needs to temporarily "see" the entire drive as part of the file structure so while it's running you will typically have zero free space.

[Why Syzygy]

2. Thanks.

Can you imagine why it goes past 100% complete?

[pokerfan]

3. Not really

Could be an error in the program. Perhaps something to do with file allocations. There is always overhead involved in file management, so many bytes reserved for allocation tables, journaling, etc.

[Why Syzygy]

4. ah.. yes I bet that's it. thanks again. nt

[EvolveOrConvolve]

5. Not all "shredders" work as well as advertised

If you want your information to be completely irretrievable, the software should meet U.S. Department of Defense guidelines. I haven't looked into the product you're using, but I've never heard of it - many of these software packages promise a lot more than they can deliver because, honestly, how will the average consumer be able to tell if their data is really and truly deleted? I've met some pretty smart forensics people who can pull files from a hard drive, even though the sector on the disk where the file was stored had been written over by another file. There are some tricks of physics that allow that to happen.

I use DBAN: http://www.dban.org/. It's approved for use in the government agency for which I work, and is the only one we have approved. Granted, it completely wipes the drive instead of performing the same task on single files or folders, but it's a pretty safe bet your data will be gone forever after wiping the drive with DBAN.

Just my 2 cents. Most likely the product you listed works well enough for your purposes, but only because the information you want securely deleted isn't really important enough for someone to put the time into retrieving it.

[Why Syzygy]

6. It's a tool included

in Revo Uninstaller, which is a great product.
I just want to free up space, not cover illegal activity.

Their site:
Evidence Remover

Deleting your files and folders does not mean that they are gone forever. When you empty Windows Recycle Bin your files and folders are just marked as deleted but they are not erased physically. There is a chance to recover deleted data from a 10 years or older PC and this data may be very important and confidential. With any recovery tool or un-delete program you can easily get back your important documents and other files that you have deleted. And here comes the Evidence Remove tool of Revo Uninstaller. Evidence Remover will eliminate all chances to get data back from your hard drive. It will erase forever files and folders, which already have been deleted but left physically on your hard disk. No matter what tool you or somebody else will use to recover the data, including professional and expensive recovery and un-delete tools, the result will be always one and the same - the data erased with Evidence Remover is impossible to recover!

Limitations: After using the Evidence Remover tool the deleted files and folder names are still visible to recovery tools, but not recoverable as a file or a folder.

[EvolveOrConvolve]

8. If Revo includes DBAN

it's probably a pretty good product. They might also use the DBAN algorithm to delete files and folders, because DBAN is open source and an excellent piece of software.

[pokerfan]

7. Plus DBAN is open source

If any application ever called for open source it would have to be disk deletion. That and voting machines, I guess. It's the only way to guarantee that the program is really doing what it claims to be doing.