Can a small industrial demagnetizer erase a hard drive

Reminds me of the ex girlfriend of one of my buddies back when Radio Shack had a real computer push. She was their computer guru. Usually she asked me or my buddy for help with anything as we were real computer nerds back then. One day she didn't ask us when she decided to erase an old Seagate MFM hard drive with a mag tape bulk eraser. When she powered it up you could hear that drive screaming 4 shops down the walkway in the mall.

Not nearly strong enough for succesful erasure. Severe mechanical destruction is the only safe way,

A pickaxe stroke strong enough to both penetrate and mechanically distort the disk platter is a good start.

CD / DVD destruction is much easier see

Jim

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.

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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.

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.

It shouldn't really matter. Is the data on them important enough to anybody for them to bother to go to the trouble to read it anyway?

If they were mine, I'd take the bandsaw to them. Or crush them.

But just opening the cover and scraping the disk with a screwdriver will do it.

And to me, it'd be a heck of a lot more fun crushing them in the press than running a silly lil' ol' demagnetizer over them, which probably wouldn't have any effect anyway, since the steel covers will "short out" the magnetic field.

Have Fun! Rich

If you do this, put some kind of backer plate under them so you don't chip or crack the concrete.

Good Luck! Rich

Hard drives have very powerful magnets in them.

i

My brother uses a 1" neodymium magnet to find conduit and nails in walls. He is an electrician. One day he forgot the magnet was in his pocket and picked up his laptop that was running on batteries. He said that as the laptop came near his pocket he heard the windows shutdown song and his laptop never booted completely again.

Using Spinrite to look at various cylinders on the disk, I determined he wiped a number of cylinders out in an instant.

I suspect that if you power up the drive and use a similar sized magnet and do a slow wipe with the magnet on top and bottom of drive that disk will be dead forever.

I hope you are not involved in anything that requires that level of paranoia. A hit with a hammer on the controller board would be enough to stop the curious at the landfill.

I have a pile of drives I need to kill for good practice, I'm going to mine them for magnets. That might be a good job for your son. Give him some torx screwdrivers and tell him to take them apart and find the magnets. By the time he is done, that drive will be dead enough unless the FBI or CIA wants you for something. ;)

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

Yes, but the flux of the head positioning magnets is very carefully controlled so that NONE of it flows through or across the platters, and NONE of it influences the read and write heads. The flux of those strong magnets is concentrated through the gap where the "voice coil" actuator armature works.

laptop that

a number of

a slow wipe

A hit with

screwdrivers and tell

There is nothing super serious. I do not even know what is on them. But think, saved passwords in a browser, SSH keys for accessing my computers, saved emails, newsgroup posts etc.

Nothing super serious. I encrypt things that are sensitive, such as my plans for surprise presents and so on. I would not want the other stuff to fall into wrong hands, though.

I think that you are right that destroying the controller boards oughta be enough.

I will just crush them with a press. It is a bit painful because the hard drives are very strong, needing to contain shards of glass etc. This is wy I was looking for something less destructive.

his laptop that

wiped a number of

do a slow wipe

A hit with

screwdrivers and tell

drive will be

Blue tip wrench - slice them across and they are DONE.

Or the band saw. Half should be good enough, quarter if you are paranoid.

his laptop that

he heard the

wiped a number of

do a slow wipe

paranoia. A hit with

screwdrivers and tell

drive will be

Not if the platters are made of glass.

i

I wonder if the answer has changed any from the last time this was posted.

The heads and electronics would be all fried before the drum would be erased.

LOL

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his laptop that

he heard the

wiped a number of

do a slow wipe

paranoia. A hit with

screwdrivers and tell

drive will be

Better than 90% are aluminum. Of all the drives I've destroyed over the last 20+ years, I've never run across one with glass platters. Wer're up in the hundreds - ranging from full height 5 1/4" SASI drives to 2 1/2 inch sata drives.

Likely not strong enough to *securely* erase the data. It might weaken things enough so the computer would have difficulty reading the disk, but for someone taking serious data-recovery measures, they would have no trouble.

Note that the tape degausser for 9-track data tapes which I have has poles above and below the tape (so the field goes right through the tape), and the tape reel is spun between the poles while the platform slowly moves out so the whole of the tape passes between the poles.

And -- there is a series capacitor in the tape degausser connected to resonate with the inductance of the coils (at 60 Hz, of course) to maximize the field (with a warning of extreme voltages within the case) -- so unless your industrial demagnetizer is constructed on similar lines, the odds are that it will not do very well at all.

And -- I'm not sure about the coercivity of the media in the drives -- it may take a stronger field than the old mag tapes took.

Give the kid(s) some torx screwdrivers, and a challenge to strip each drive as far down as they can -- saving the metric screws, and the bearings, and especially the head servo magnets. Most kids love to take things apart, especially male kids.

Or -- take them down to your favorite outdoor shooting range, and see how many stacked up drives you can send various calibers through. If you get through all of them in a single shot, you have securely erased them *very* quickly.

Or -- if you have always wanted to play with thermite, put each drive under a pile of thermite, and light it off. :-)

Enjoy, DoN.

[ ... ]

Yes -- the SSH keys and passwords alone justify this

Understood.

BTW Have you read about the solid-state drives? Things like CF cards and thumb drives have a limit on the number of writes before they start losing data. The solid-state drives have an elaborate logic card which re-maps "sectors" with every write, so just because your OS is writing to the same sector every time you access a file to read it (e.g. updating the last-accessed date in the inode in unix flavors), the drive's logic swaps that around the whole drive over time, thus minimizing the number of writes on any given physical "sector".

As a result, you really *can't* overwrite the whole drive to erase it -- physical destruction is the only way with those.

As I just suggested in a previous post (which was not there for you to read by the time you posted this) -- take them to the range, and try penetration tests with various rounds.

Enjoy, DoN.

If you just want to insure destruction, dismantle for the magnets, drop the platters in the driveway and slide them back and forth over the asphalt or concrete a few times with your foot. That'll hose things but good and raise more than enough burrs to make even the NSA weep over trying to recover much. (I think...)

Jon

The strong magnetic field might destroy the heads themselves. They are tiny and use very small wire in the loop.

Mart> >

Is it a security issue ? - a few screws takes off the back and then you just bend the platter(s). Easy.

Mart> I have a little industrial demagnetizer from a grinding shop. Can this

Indeed. Very well stated.

Gunner, posting from a restaurant via cellphone hooked to cell phone

Whenever a Liberal utters the term "Common Sense approach"....grab your wallet, your ass, and your guns because the sombitch is about to do something damned nasty to all three of them.