Secure hard disk content erasing?

[Stefan]

Hi,

Does anyone know about a recent study/article/report about fully erasing PC hard disk content by software tool only? I am facing rather wasteful constraints in my organisation when needing to recycle PCs that once contained sensitive information. Tools like Eraser (http://www.tolvanen.com/eraser/) do a good job in deleting whatever is accessible by software. Is this enough when using modern hard drives?

I wonder, if the findings of the Gutmann article from 1996 still apply for today's technology. (http://www.usenix.org/publications/library/proceedings/sec96/full_papers/gutmann/).

Many thanks for help, references or tips.

[David_Jones]

Hi Stefan,

I may be missing the point here, but if you just want to be absolutely, 100% sure that all old data on any given disk is erased, then all you have to do is delete it, and then fill the disk with junk to actually overwrite the data.

When you delete something, the normal effect is for the marker in, say, the File Allocation Table to be deleted, but the data is still on the disk (just difficult to find).

If you then fill up the disk with some junk data, the original information will get overwritten, thus destroying it for all time.

My normal method for filling up a disk with junk is to create a text file with just a whole load of XXXX in it, then recursively copy two copies of the file into folders, thus doubling the disk usage every round. It will never take too long to fill up a disk no matter how big it is, and it works the same for a HDD, Floppy, CD etc. Of course, if it is a Floppy or CD, you might want to just physically destroy the media since cost is often not an issue.

Don't forget to delete the junk folders and files when you are done to free the disk space for use again!

Hope that helps,

David.

[nightfishing]

Eraser is very secure; just use a minimum of 7 passes and the data will be unrecoverable.

It does to free space exactly what the previous post mentioned, it writes random data over the disk and then leaves the disk clean.