Powerful magnet to destroy HDD?

[88keys]

I know an ordinary magnet won't effectively destroy a hard drive as it still can be repaired. I have this old industrial magnet that I got from an old job that I once had. It was used for picking up heavy die sections. I used to use it personally for case modding because it would hold metal pieces together like a clamp for when I needed to apply super glue.

It's pretty big too. About 10"x6", and it actually takes some strength to pull stuff off of it.

Say if I left a HDD on it for 8 hours, do you think it would be toast?

 

[BrightCandle]

A very high powered electromagnet, the sort found inside of physics university departments might have enough energy but a magnet you can pull off with your hands is not going to clear a hard disk. Seeing as how all you need to do is fill the disk with zeros anyway its not exactly a big deal to destroy the data on a HDD.

 

[alangrift]

Depends how strong the field is on the magnet it might take some force to pull it off but that has nothing to do with the distance at which it attracts but I think it should do the job.

 

[Elixer]

Well, if you want to experiment, it might cause some data loss, but then again, without knowing the strength of it, it could just pick up the HD and do nothing else...
Would be better (and much more fun!) to open the HD up, take hammer, and smash the platters.

 

[master_shake_]

i tried an electromagnet from an air conditioning clutch... left it on there for a good 5 minutes... data was still intact.

the sledge took care of that.

interesting side note: seagate's (power of one) campaign is a crock of shit.

a 2tb drive with 3 platters, not 2...

 

[KingFatty]

At a low level, the magnetic field will be blocked by the metal shield of the drive, and won't penetrate into the disk inside. That's the first burden to overcome before you can use magnets to wipe data.

I think the housing of the hard drive is fully enclosed on all sides by metal, but here is a picture and info showing how u-shaped metal shielding reduces magnetic field penetration:

Quoting from http://www.maximintegrated.com/app-notes/index.mvp/id/5471

U-Shaped Shield
Bringing the sides of the shield down to form a U-shaped structure (see Figure 5) reduces the flux density to 25mT (center) and 29mT (15mm off center). The field lines tend to follow the mu-metal structure and penetrate the PCB only in two places.

At the next level of strength of magnetic fields, the field will be able to affect the data stored on the drive, but the drive will still work and be re-usable.

Then you can get a field strong enough to induce current in the circuitry of the drive controller, and even damage the chips and render the drive unusable.

Going further, you can get a field strong enough to physically crush the drive.

Finally, you can get a strong enough alternating magnetic field to melt the drive to slag, like this (please use this method if you want to ensure all data is wiped):

http://www.youtube.com/watch?v=3iBztmCuwgk

 

[C1]

With permanent magnets, the HDD case acts as a shunt for the lines of force.

At work we had a device that used EMP. It looked like a small blast furnace on a 4' pedestal. You put the HDD into the thick walled magnetically and RF shielded interior and closed a thick shielded door that was something just like you think you would see if it was a blast furnace.

You then would turn some interlock switches that allow arming the device. Hit the "red button" start timer and count down. Were then warned to stand back as large capacitors charged.

At about 30 seconds the system discharged with a loud bang (noise level of a 22 pistol) - capacitors discharge into an EMP producing transducer system effectively completely erasing the HDD.

The HDD was probably ruined internally. Once I tried to format one that had been "cleaned" using the EMP device, but it was dead as a door nail.

You can buy NSA/DoD approved cleaner units, but they are expensive (as much as a car).

 

[Blue_Max]

Any magnet powerful enough to obliterate the data would probably also damage the mechanics of the drive itself, rending it useless.

Why not simply use some heavy-duty formatting software that'll "destroy" all data by writing the entire disk with "1" then the whole disk of "0". One pass is enough to stop your average competent "hacker" - several passes will eliminate all data from even data recovery experts who charge $thousands.

 

[Red Squirrel]

I once built a device to degaus drives. Problem is I had zero way of validating that it actually did the job well enough that it could not be recovered via specialized equipment.

So I find physical destruction is always the easiest and easier to guarantee. If the drive still spins up I usually just take a semi sharp object and slowly slide it over the platter like a record player arm playing a record. I'll also score it from centre to outer edge 10-20 times in different locations. Do this on each platter and each side, then bend them, and I really don't think anyone can recover that. Even the NSA would probably have trouble. Throw the platters in different trash bins at different times. Make sure there's no finger prints on it.

 

[Blue_Max]

...I hate seeing the waste of physically destroying useful drives and sending them to toxic landfills when a day or two of data over-writing would certainly do the job and the drives could be put back in service elsewhere (and with users writing data, only further ensuring no possible recovery.)

 

[BrightCandle]

There is not a single commercial company capable of recovering a disk that has been simply cleared to 0's just the once, destroying the disk is dramatic overkill considering how easy it is to reliably empty a disk for resale.

Maybe there are government agencies that want the contents of your disk and would take it apart and use specialised hardware to read it, but beyond that no one else is even remotely able to get passed a simple 0 write which takes a couple of hours.

 

[John Connor]

DBAN or Ccleaner will erase it just fine. I really don't think a magnet will do the job. But a magnet could wipe the strip on a credit card.