[quickben]

No, what he is saying, is that moving magnetic field, induces current, and can mess up the cheap power supply and/or other components, which can then mess up the drives.

In a server, the power supply is on the other end of the chasis. In a laptop, it's a lot closer to the internals.

> I don't buy that either.

Theory: https://en.wikipedia.org/wiki/Electromagnetic_induction

The forward model: https://www.youtube.com/watch?v=UL_ryxub-RA

The reverse model: https://www.youtube.com/watch?v=J9b0J29OzAU

The big ones: https://en.wikipedia.org/wiki/List_of_conventional_hydroelec... Note: the Three Gorges: 22 GW

For comparison, nuclear power: https://www.nei.org/Knowledge-Center/Nuclear-Statistics/US-N... Largest U.S. nuclear plant: Palo Verde (Arizona) produces around 4 GW.

For home applications: http://www.ebay.com/bhp/hydro-electric

[ars]

Do you understand what you are saying?

A person, moving a magnet near a single wire - not even a coil - is going to induce utterly insignificant amounts of electricity.

You'd need lab equipment to even detect it. It will do absolutely nothing whatsoever to computer electronics.

[quickben]

Open a powesupply before your next reply.

[ars]

What am I supposed to reply to?

Instead, why don't you take a multimeter and see if you can measure any voltage (never mind current) by moving a magnet, by hand, near a single non-coiled wire.

[quickben]

Well honestly, I wrote that because I wasn't sure what to reply. I'm taking in five comments about power supplies, tons of wrapped wire, and I get a reply about a single wire.

Anyways, I apologise for being snappy.

[harshreality]

Nobody is suggesting that electromagnetic theory is false. The question is whether there's really a danger from HDD magnets in motion relative to nearby electronics or HDD platters.

- HDDs often live right next to each other (separation of roughly 1cm, front to back).

- Power supplies and their induction coils are right next to the drives in some cases, including for instance consumer grade NAS boxes.

- HDDs tend to have a coil of wire, too.

If HDD magnets overwriting nearby HDD data was a thing, it would be happening all the time.

If HDD magnets in motion in certain orientations were inducing damaging currents in nearby HDDs or in nearby power supplies which then damaged connected components, that would be happening less often but still all the time. Not all chassis designs have power supplies at the opposite end as the disks, and some applications like consumer NAS boxes have them in close proximity to each other.

[quickben]

The magnetic head that writes to the disk, is fairly small and close to the platter. The flux is very contained. So that part seems negligible in the overall scheme of things.

[harshreality]

Who's talking about the field from the magnetic read/write head(s)? This is about the permanent magnets built into spinning hard drives, and what those permanent magnets might do to nearby disk platters, or, when in motion, might do to coils of wire in nearby electronics.

Either some extremely unfortunate and rare positioning and orientation and motion of the magnet occurred, which barely exceeded the design limits of the drive or power supply or other circuitry (or maybe the laptop hdd or circuitry was shoddy and shouldn't have had a problem but did), or this is a major problem that's gone unappreciated among computer and NAS builders for decades, or it was an extremely unlikely coincidence.