On 4/4/09 3:57 PM, "Wallace Adrian D'Alessio" <[email protected]>
Broadcast into the ether:

> Kyle, it was my opinion that a strong enough mag field would erase all
> formatting and make it unusable. Another lister was of the opinion that since
> these are SCSI they could still be reformatted. What do you think?
> 
> I had an IDE external wrongly low level formatted at the university iT guy
> recently. It has been brain dead since.
> But then it is not SCSI. I havn't dealt with SCSI for a while so I can't
> remember the ins and outs but it seems I had to worry about sector mapping
> even on SCSI. 

It was my job for about 3 months at Lawrence Livermore Laboratories (science
and weapons development). We literally had to securely destroy hundreds of
Mac¹s and PC¹s during their upgrade.  We did so ³lovingly.² Instead of just
tossing the entire units into the gigantic (think 4 dumpsters big) metallic
shredder we removed the drives and got permission to donate them to
charities and non profits and even give some to our friends and such.  AS
LONG AS THE HARD DRIVES WERE GONE AND THE FLOPPY DRIVES ALSO REMOVED.  Caps
on purpose.  We found at the complex a degauser that literally had a handle
and was smaller than a dustbuster.  I wish I knew how it worked. It was
beige.  It had a coiled AC cord.  It was rectangular and the handle was on
the top.  Below the handle was about 4 inches of something.  So picture a
rectangle with a handle on top.  About 8 inches long and 4 inches wide with
a cord and a button you depressed with your thumb.  Since scheduling time
and use of the metal shredder was really complicated...different area of the
facility, security clearances etc we used this ³thing² do DESTROY hard
disks.  They were rendered USELESS in an instant.  We would take out the
floppy and smash it with a 3lb. Sledge, the set the degausser on top of the
drive and hit the button, wait 3 seconds or so and blam.  Gone. Dead.  Since
this was relatively new (1995?) we had to have it tested to make sure the
data really was gone.  This was weapon development stuff.  Serious top
secret stuff.  We gave the drive to the forensic data recovery guy and said
³go for it.²  About a week later he He came back to our little testing are
and literally said to us, and I remember it like it was yesterday ³what did
you and Trevor do to this drive?²  He could not get a single bit of info off
of it.  It was the first drive he had ever had do this to him.  He was
flabbergasted.  We got the clearance and just started popping these drives
one after the other.  Hard drives are just devices with a controller board
that have metallic discs inside that have have a sector positively or
negatively charged to create a 1 or a 0.  This little device did something
so catastrophic to the drives that they were rendered useless.   And the
data guys pulled the platters and put them on recovery units to see if we
had just damaged the controller board.  Sometimes we would stack up hard
drives and play bowling.  Or dominoes...your tax dollars at work.

The magnetic signal written to a sector can be read (remnants of it) even
after writing zero¹s to it more than 10 times.  It is just more difficult
and takes more time.  What they do now is layer the zero writes and follow
the patterns under them. Similar to digging in sedimentary soil.  You are
looking for a 1 inch layer of quartz but there is no quartz to be found.  So
you dig deeper and deeper and deeper until you find the layer of quartz (or
information  in this case) and then you set up the unit to data mine or real
world mine at that level. I can¹t wait for the new organic drives to come
out.  I wonder how we will accomplish the same thing?

The moral of the story is that you probably can not safely EVER remove the
data off of a hard disc.  Writing Zero¹s to it once will deter 99.99% of
most people.  I hand drives off after one write all the time.  But if you
ever want to truly make a drive unreadable take it out back and bash it into
little pieces.  It can be fun.  Anyone see the printer scene in ³Office
Space.²  

Kyle Hansen
-- 
This is the way the world ends...not with a bang, but a twitter.


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