On 5/25/2011 10:30 AM, Ignoramus23924 wrote:
I have a little industrial demagnetizer from a grinding shop. Can this
thing erase contents of hard drives securely? Or the magnetic field is
not string enough? I have a pile of old HDs awaiting destruction.

THe alternative is my press, which is more of a PITA.

Thanks

Take them outside, put them on a concrete sidewalk, give them 2-3 good
hits with a sledgehammer. Drives made in the last ~10 years have
tempered-glass platters that will shatter totally. Drives older than
that have metal platters, but if they can't spin, they won't work. (Also
if the controller circuit board gets smashed up, only the manufacturer
probably has the ability to get or make a new one)

Then you can just toss them in the trash -- but the frames of many are
aluminum, if you recycle.

-------

If you want to erase a working drive completely, just hook it up as a
slave drive, get a random-over-writer like Eraser and do a 1X random
over-write of the entire drive. Or go 3X if you want to get crazy, but
nothing more is needed. It's not difficult, it doesn't take that long
and you can have that going while still using the computer.
http://eraser.heidi.ie/

Eraser is free and has a bunch of overwrite options, from 1 to 35
passes--but if you look at the list, you will see that many government
and military standards are only a 3x random overwrite.

,,,,,,

The way that most OS's restore previous versions of files is by an
operating system feature, not by any technical aspect of the drives
themselves. The OS does this by writing each new version at a different
space on the drive. If you randomly-overwrite the whole drive even just
once, ALL the versions will get corrupted.

If even just the /previous/ drive write (in any single location) could
possibly be recovered in any easy way with only the drive's own
read/write hardware, then the drive would have 2X the capacity that it
really does, and the hard drive companies would be capitalizing on that.
And they're not.