Register FAQ / Rules Forum Spy Search Today's Posts Mark Forums Read
Go Back   MacRumors Forums > Archive > Archives of Old Posts > General Mac Discussion

 
 
Thread Tools Search this Thread Display Modes
Old Nov 18, 2004, 03:26 PM   #1
Toe
macrumors 65816
 
Toe's Avatar
 
Join Date: Mar 2002
Magnets, Hard Drives, and AlBooks

Getting a magnet near your hard drive will toast it, right?

Well, if you have an Aluminum PowerBook... take a paper clip and touch it to the latch-release button on the front. Move it around a little...

WTF?

That magnet is for pulling down the latch hook from the top. But what is it doing so close to the hard drive? Isn't that a problem? It seems like a pretty strong magnet....
__________________
Have MBP and iPhone. Have operated almost every Mac model.
Toe is offline   0
Old Nov 18, 2004, 03:44 PM   #2
jeremy.king
macrumors 603
 
jeremy.king's Avatar
 
Join Date: Jul 2002
Location: Fox Lake, IL
Give this a read.

http://seclists.org/lists/fulldisclo.../Jul/0596.html
jeremy.king is offline   0
Old Nov 18, 2004, 03:47 PM   #3
patrick0brien
macrumors 68040
 
patrick0brien's Avatar
 
Join Date: Oct 2002
Location: The West Loop
Send a message via AIM to patrick0brien Send a message via Yahoo to patrick0brien
Quote:
Originally Posted by Toe
Getting a magnet near your hard drive will toast it, right?
-Toe

Eee, err. Well, not exactly. Yes, an HD is a magnetic medium, but other than that quite different than a magnet. First off, a layman's magnet is essentially a block of ferrous particles that all point in the same parallel direction - that old discussion of north and south poles (dipoles). If you take that same block and point each dipole in a different direction, the magnetism effectively ceases because it is no longer focused.

In a hard drive the dipoles are highly sequestored. Think of a disc that has billions of little magnets stuck to the surface - each with their own set of dipoles.

In order to 'screw up' a particular magnet, you need to hit it with a magnetic field that intersects the direction the dipoles are pointing - preferably with a field at 90 degrees, though less an angle can still repoint the dipoles. Also let's not forget that each magnet has but a simple bit of information to carry - a bit. A 1, or 0: Yes or no: Magnetized or not. You'd need to really hit that block hard to change it's state enough to change that information. And you'd need to do it billions of times.

Additionally, to really screw up the dipoles of the billions of tiny magnets that make up the business layer of a hard disk platter, you'd need to hit each with a magnetic field equal to or greater than the field used to align them in the first place - the R/W head on the slider (very strong, microscopic, concentrated field), and the same basic size.

So! What does that mean? Well, to really kill an HD, you need to go out of your way, and degausse it. Meaning to get a field strong enough, yet wild enough to affect so small a magnets, you need to creat a strong flux, a powerful, vibrating, self-cancelling field, and get it really close.

So don't worry. BTW, that little magnet you found is on of two - the other, likely located along the right side of your screen, is to enable the computer to know when it is closed.
__________________
This comment has been edited for Content, Formatted to Fit Your Screen and to Run in the Time Allotted

Last edited by patrick0brien; Nov 18, 2004 at 03:53 PM.
patrick0brien is offline   0

 
MacRumors Forums > Archive > Archives of Old Posts > General Mac Discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Similar Threads
thread Thread Starter Forum Replies Last Post
Tool-less 3.5 hard drive enclosure that supports 4TB hard drives Sossity Mac Peripherals 3 Jul 6, 2013 02:03 AM
naming external drives, hard drives, thum drives for best compatability Sossity Mac Peripherals 1 Apr 5, 2013 03:11 AM
Bare 3.5 hard drives, & enclosures vs buying all in one external hard drive Sossity Buying Tips and Advice 16 Feb 12, 2013 11:10 AM
Hard back-cases with magnets? (Ipad 3) Avik iPad Accessories 3 Aug 13, 2012 12:12 PM

Forum Jump

All times are GMT -5. The time now is 12:10 PM.

Mac Rumors | Mac | iPhone | iPhone Game Reviews | iPhone Apps

Mobile Version | Fixed | Fluid | Fluid HD
Copyright 2002-2013, MacRumors.com, LLC