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As per the title, would these magnets

Magnet Image

be enough to damage a portable hard drive such as this Seagate GoFlex

HDD Image

if left next to each other for longer than, say, 20 minutes?

Thankfully, this is all hypothetical at this point as I have kept them apart to date and my question comes to mind if the two fell on top of one another whilst in a backpack or bag.

Scott - Слава Україні
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Luke Godwin
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2 Answers2

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Considering the drive itself contains a magnet that I would expect to be far stronger than these are, I would doubt there to be any issues from them coming into contact. It's largely a myth that hard drives are easily wiped by a magnet (VHS, tapes and floppy media are far more likely to). In fact, a test was done here involving huge neodymium magnets, far more powerful than most magnets you will have, which caused zero data loss at all (more of a chance of mechanically damaging the drive due to the power of them if they'd been closer to the read heads).

I wouldn't state it's impossible for some form of damage to occur, but it's very unlikely. Don't worry too much about it, but keep them separate if you can.

Jonno
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    Not to mention, Harddisks are encased in a metal casing which essentially are farahday cages. – LPChip Feb 15 '16 at 08:23
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    More commonly spelled [**Faraday cage**](https://en.wikipedia.org/wiki/Faraday_cage). – Scott - Слава Україні Feb 15 '16 at 10:06
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    I thought a faraday cage (which is mesh) is distinct from a simple plate of ferromagnetic material - which acts as shielding? – Journeyman Geek Feb 15 '16 at 10:31
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    @LPChip [Faraday cages do (almost) nothing to magnetic fields.](http://physics.stackexchange.com/questions/38759/does-faraday-cage-block-magnetic-field) Also note that [electromagnetism is different from a static magnetic field](http://physics.stackexchange.com/a/89090/56528). – Bob Feb 15 '16 at 13:16
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    Should be noted that the powerful magnets inside a hard drive are actually [to control the actuator arm](http://i.stack.imgur.com/2Cnc2.jpg) and not the read/write head itself (which is an electromagnet that's not powered when not in use). Also, *just* the fact that there's magnets inside doesn't mean external magnets of equal strength will have no effect - the orientation of the field could make a big difference. It just happens that in this case these magnets are too weak to do much. – Bob Feb 15 '16 at 13:21
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    I'd worry most about the magnet causing a headcrash (especially when exposure happens while the drive is operating). The experiment you cite deliberately positioned the magnets away from the head. (Though the OPs magnets are likely much too weak) – CodesInChaos Feb 15 '16 at 16:21
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    @Bob: Jonno may have been referring to the magnets in the drive motor (that spins the platters). These are indeed very powerful magnets and very close to the areas where data is stored.. Not sure what techniques are used to keep these powerful fields from affecting the data on the platters. Probably effectively shielded by giving the fields a preferential path away from the platters. –  Feb 15 '16 at 17:12
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    @JourneymanGeek a solid enclosure is just as good as a mesh one (in fact better). But put another way, a mesh enclosure is as good as a solid one (for wavelengths longer than the mesh pitch), uses less material, weighs less, and allows visibility and ventilation. – hobbs Feb 15 '16 at 18:53
  • @JDługosz ...two of my links point to physics.se, one points to i.stack.imgur. I don't see any pointing back here? – Bob Feb 15 '16 at 21:04
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    Note that the magnet to actuate the arm is actually two magnets in halbach array formations, directing the magnetic field into the arm, leaking a minimal field to outside (and into the direction of the platters) – PlasmaHH Feb 15 '16 at 22:31
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If you want to damage a harddrive with a magnet, the drive needs to be running and busy writing/reading stuff. And even then you need a damn powerful magnet.

I once disabled a harddrive with a 10x10x15 big magnet, and I believe it's more damaged because the internal mechanics got twisted/damaged during reading writing. I suspect a head crash

All in all you need a pretty big magnet.

Want a magnet that is guaranteed to destroy a hard drive — or for that matter, a CD/DVD drive? You need something like this 2-inch N52 neodymium disc magnet that has a pull force of approximately 450 lbs. Get your hand clamped between this and a piece of magnetic metal, and you could lose your hand. This won’t just erase the hard drive, it will wreak it, along with the CD/DVD drive and any fans.

http://www.forbes.com/sites/adriankingsleyhughes/2012/11/28/can-a-magnet-destroy-a-pc/#3c30672856a2

Tschallacka
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