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Can I erase my HD with a big magnet?

by Samhri / March 23, 2007 10:19 AM PDT

I have an old HD that won't boot but may have some sensitive data.
Will holding a magnet on it render it unreadable?
I just want to dispose of it and not worry about someone reviving it.

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May as well use a hammer. Here's why.
by R. Proffitt Forum moderator / March 23, 2007 11:07 AM PDT

A magnet could erase the servo track which can't be rebuilt without a trip back to the factory so the drive is effectively smashed. So a hammer would result in the same dead drive.


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Specifically, no.
by Coryphaeus / March 24, 2007 7:46 AM PDT

To erase a drive you need a high frequency AC magnetic field. Bringing a powerful magnet close to a drive will "corrupt" the data as the individual flux lines will change certain bits. The drive may be unreadable, but can be reformatted and possibly repaired. A hammer is a better erase device.

And I know of where I speak. A few years ago I had the opportunity to acquire the magnet out of an IBM 370 Hard drive unit (circa 1980). This was one of the 18", 6 platter drives with a linear motor. The linear motor magnet actually weighs twenty pounds and is about 8X8X4 inches. A real beast. As a test I placed a VHS tape close. Still played. I then put the tape on top of the magnet and let it sit. It still played. I then investigated how magnetic tape, and subsequently hard drives and computer media worked. And what it takes to erase them. High frequency, or rewriting the bits.

BTW, it will totally screw up a CRT TV from 20 feet away. This is one bad magnet. AlNiCo.


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Strike an arc with a mig welder on the HD case
by madtownidiot / March 28, 2007 6:53 AM PDT
In reply to: Specifically, no.

that will produce enough of a magnetic field to polarize the entire drive

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by rsternb / March 30, 2007 9:38 AM PDT

If the drive is already ready for the trash - then yes - use
the magnet. set it on top and leave it for a bit - then move it
around. turn it over and put it on the circuit board for a minute.

you now have a door stop.

the drive will deff never work and the data is truly messed up.

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Better safe than sorry.
by brycematheson712 / March 30, 2007 10:36 AM PDT
In reply to: MAG ERASE

A magnet may work, but unless you're going to plug the drive back into another computer to test it, I wouldn't trust it 100% completely.

Like stated above though, better safe than sorry, and just use the Hammer method. Besides, it's more fun.

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Use a hammer?
by Gtkid2002 / March 30, 2007 11:52 AM PDT

If you dont really like getting your hands dirty, just attack it with a magnet, yes, but also try cutting cables on it. Cutting just 2 parts on one cable will render it pretty much useless. If it still works, you could always try doing a full format, then hammer, then magnet, then cutting cables. That way NOTHING would survive.

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Use a Hammer?
by arshnar63 / March 30, 2007 1:41 PM PDT
In reply to: Use a hammer?

See my reply to Hard Drive Crusher
Eraser programme is much more practical. Second solution- put
drive in an old computer, go online, click every pop up, porn ad, and adware you can, and leave it to fill up with spam and junk!

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alternate way
by denvermorgan3000 / August 25, 2015 3:24 AM PDT

There is one easy way out im sure you are near a bridge electronics do not like water esp salt water.

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Erasers, hammers and magnets...OH MY!!!
by btljooz / March 31, 2007 4:58 AM PDT

Since the thing is unusable anyway, what you need to do is destroy the platter itself. As long as that platter is around it CAN be forensically decoded by a motivated/determined entity. Therefore complete platter destruction is most definitely preferred.

Platters are made of extremely hard metal alloy making the hammer method uselss. All a hammer does is break the components of the hard drive AROUND the platter, possibly but not likely, leaving any real marks on it. It (the platter) can always be re-installed in different housing with a working "reader" to allow it to be read.

Erasers, can be effective, but work on the priciple of over-writing the data with any number of layers of random patterns 1s and 0s. Data forensics have been known to be able to retrieve data even through all those layers.

As mentioned it would take one '7734' of a magnet to affect the magnetic field on the drive. How many people have access to one of these UberMagnets anyway? And the results can be dubious at best?

Yes, drilling of holes in the platter can help but there will still be portions of the platter left and who can tell if the holes drilled are in the places on the platter where the sensitive data is?

This is why one should dismantle the hard drive and physically destroy the platter itself.

Now is when a welding torch, preferably a "plasma cutter", can come in very handy. If you know someone who is a welder or mechanic ... someone who has a torch capable of extremely high heat ... all that needs to be done is to instert the platter into a vise (after you've taken your frustrations out on it with at least an eight pound sledge hammer ;)) and melt it into oblivious ashes with that torch. Just be sure you either do this yourself or WITNESS it being done and you'll have nothing to worry about because it's pretty hard to "read" ASHES!!! Grin

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Erasers, hammers and magnets...OH MY!!!
by Alain Martel1 / March 31, 2007 6:11 AM PDT

I totaly agree with you. Short of melting or burning the platers, carving the whole surface with some power tool is the only way to realy kill any censitive data that may live on the drive.
Deleting and emptying the trash is only good against casual recovery.
Repartitioning and reformating can twart a hobyist.
Erasers are somewhat effective against moderately dedicated persons lacking proper equipment.
Against forencic and high-teck criminal, only the complete destruction of the support will ever work.

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Destroy Hard Drive
by Wheelboss-216704861132298 / March 31, 2007 6:16 AM PDT

Things you need:

Circular saw
chain saw
screw driver
baseball bat
golf club
(not really all of this)

Unscrew the hard drive and beat and break the heads and disks of the hard drive.

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In other words...
by Wheelboss-216704861132298 / March 31, 2007 6:20 AM PDT
In reply to: Destroy Hard Drive

In other words pry or break into the hard drive and smash everythng having to do with it.

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Destroying HDD.
by cheeseisclever / March 31, 2007 6:40 AM PDT
In reply to: Destroy Hard Drive

What's wrong with the good
old fashioned fireplace, HappyHappyHappy
Blow Torch,
or Gas Stove.


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More on DHDD (Destroying Hard Disk Drive)
by Wheelboss-216704861132298 / March 31, 2007 6:56 AM PDT
In reply to: Destroying HDD.

Battering ram
gun powder
serated knife ^^^^^
jig saw
plasma torch

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by ollies6 / March 31, 2007 7:14 PM PDT

LoL sounds like fun, must find a hard drive to smash

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flouroantimonic acid?
by GoneOnAcid / September 29, 2016 5:45 AM PDT

how about fluoroantimonic acid? or Magic acid? i suppose an M60 could do the trick too.

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by old_fella / August 6, 2010 8:51 PM PDT

I agree with most of what you said however I must urge caution.

I speak from experience when I say that some platters are made of glass!!!

Two years I had to destroy over 30 dead drives of varying ages. I dismantled the cases, removed the platters and cut them into small pieces with metal cutters. Admittedly I was on auto pilot by the time I got to the last few but one of them was made of glass. There was glass everywhere. The scary thing was it didn't really look or feel any different to the others.

If you do dismantle a drive completely watch out for the internal magnets. They are very powerful.

All the best


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Die dev/hda, die!!
by ghost_ish / February 7, 2011 7:35 PM PST
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more to add.
by valseedian / November 29, 2011 12:15 AM PST

^^^ this, this and this again.. Hits the nail on the head. multiple Large, circular (or ark for doorways ;D ), alternating direction, HighFrequency&Amperage/Low Voltage AC , in bursts, alternating poles, through a silver or copper monofilament wire, degaussing stations are the only true way to fully corrupt the data through all levels without taking it apart and heating the disk to red hot. (just getting the disk red hot is more than ehough to make it forensically impossible to retrieve data)..

if one is truely paranoid, Cut the disks into 1/4s using a sawzall (and a blade for structural steel , you'll need it), Then, drill a hole in the center of all 4, and mig weld them together on the edges and through the holes... God couldn't retrieve the data off that

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by PC_Nerd-Henry_Chan / April 13, 2007 11:35 PM PDT

don't use a magnet yet. install eraser on your pc. right click on your data and click erase. click options. click guttman and click ok. click ok/erase again to erase. after erase, open eraser in your start menu. click file>new task. then click ok. click edit>preferences>erasing. click unused disk space. click on guttman and click ok. click on task menu>run tasks.
Wait wait wait for 1 hour until finished.

Then, unplug your PC, pull out the hard drive. if you have got a screwdriver (those with the kind of plastic handle) and unscrew the hd. have some googles on your eyes. it might blow up. Some air should rush into it. the hard disk needs to be in vacumm, it won't work now. use a magnet. break the disk into two. throw it away. done!

-0- PS. if it doesn't work, don't find me. A friend of mine unscrew a mac harddisk and it broke up. i am not sure if it will blow up, take this at your own risk. or, just use some spray on the hard disk (bug spray) and throw it away. "throw!" it will blow up if there is a current, since spray is made of oil.

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dead HD disposal!
by ChinaElectronicsInsider / February 13, 2012 12:35 PM PST

If the HD had sensitive data, then overkill is always a fun option! Hmmm, I think I would take the HD completely apart, even the special screws, and then throw the non metal parts in a fire. With all the data recovery experts out there, overkill is in my opinion necessary.

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Da magnet!!
by rclampe / May 2, 2012 2:47 AM PDT

I have a high-perm magnet probly from a defunct particle accelerator, (Bought on line - you can probly still buy them). This thing will smash your finger if you get one between it and a bench vise. It cleans a VHS tape in a quick swipe. You get nothing but blue screen and ghost-free recording. After reading the other posts, I believe this will do the job. It's only about 2x2x1 inch, but I'm a little scared of it. I keep it in a safe place, but no one will steal it, cause they will think it's welded to the metal bench where it lurks to grab stuff out of your pocket as you walk by.

Anything weaker might not work, and the hammer sounds like fun.

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That magnets can erase a Hard Drive is a MYTH
by 3agle1 / May 30, 2012 3:10 PM PDT
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It is not a myth
by Yuri311 / February 12, 2013 4:25 PM PST
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fire or extreame heat.
by denvermorgan3000 / August 25, 2015 3:21 AM PDT

you need an alternating magnet but the best way get your screw driver open the drive and burn it .

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i have the similar issue some week ago.
by donbaze / September 26, 2016 8:20 PM PDT

i have the similar issue some week ago.
although my own was mistakenly shift near my pc, i mean my magnet was mistakenly put near my pc and it wipe the hell out of my hard drive!! Shocked

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