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Take a peek inside a hard drive!

July 19th, 2005
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OK, a few days ago I promised you a look inside a hard drive - well here is it!

No working drives were harmed in the making of this article - This is an old Maxtor 20Gb drive that suffered from intermittent failure that I've had on the side for a while waiting to take it apart and photograph the carnage!

The tools I needed for this job were a size 4 straight edged screwdriver and a TORX bit (number 6).

Note: I took these photos myself under less that ideal lighting. They're nowhere near the quality that I'd be aiming for in a book, but it gets the point across!

We begin by using the TORX bit to undo the screws holding the cover on the drive.

Drive makers are sneaky - they hide some screws under labels so they can tell if you've had the drive to bits!

These TORX screws hold the circuit board to the main drive body. This is the brains of the hard drive and control the operation of the components inside. Undo these and you can lift the board off the drive body.

Here are the contacts that connect the circuit board to the drive itself. All are spring connectors - no wires used.

Here the cover is removed showing the platters and read/write heads. These are the mechanical components. These platters were perfectly clean and shiny when I first removed the cover.

And here is all the electronics inside the drive. Not as much as you might think.

Never peel stickers off a hard drive - you might uncover a hole. These holes serve a number of functions - such as allowing the manufacturer to write the tracks to the blank media and calibrate the drive before shipping. Peeling the sticker from a working drive would quickly let in dirt and dust that would ruin it.

Here is a closeup of the read/write heads on the disk platters. These ride on a thin layer of air generated by the rotating platters.

This is a particle catcher. It's purpose it to catch any small particles tossed off the disk as it rotates. On a good drive this will be clean but sometimes you find small metal particles on it when the drive has suffered a head crash.

This is the actuator that controls the read/write heads and moves them across the drive.

To unto the actuator you undo the screw holding it. However, you also need to undo the platters at the same time.

Undoing the platter screws. These are TORX No. 6 too.

Platters removed along with the actuator and read/write heads.

Here's a shot showing how thin the platters are - only a millimeter or so thick! This drive is a small one (20Gb) and only contains one platter but some drives can contain many more. Still, the data density is incredible at 10Gb per side on the platter!

Here's a closeup of the bit that makes a hard drive work. This is the read/write head that writes data to the platters and reads it off - these are an amazing feat of engineering. These heads skim the surface of the platters incredibly close as it goes about reading and writing data - if they touch the platters when operating they will smash the delicate magnetic coating or even themselves, rendering the drive scrap.

This is the ultra-strong magnet powering the motor for the actuator arm.

Here is a filter that cleans the air entering the drive. A drive isn't airtight, instead it allows the pressure to be equalized in the drive but the air coming into the drive has to be clean.

Here is the vent hole on the exterior of the drive.

Removing the platter motor is tricky - you have to give the spindle sticking out underneath the drive a tap using a hammer and a center punch.

Here is the platter motor removed from the drive casing.

Here is a closeup of the platter motor coils.

Finally, here's a look at all the parts that go into a drive.

Over the next few days I'll take some more closeups of some of the more interesting components so you can get a better look at how intricate they actually are.

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One Response to “Take a peek inside a hard drive!”

  1. Windows XP..which one ?? - Forums Says:

    [...] Today, 06:50 PM You will find some good photos of an open hard drive on this page Take a peek inside a hard drive! � The PC Doctor’s blog The platters are shown on the fifth photo Depending on your system the hard drive may become a bottleneck, that sometimes happens when old drives are reused in new computers (to save money). So IF your drive is actually a bottleneck, a faster HD will of course speed things up. Something to keep in mind is also the ability to use native command queueing (NCQ). All newer hard drives and controllers support this. This is a technology that allows a better serialisation of read/write tasks (given the fact that the drive has enough cache to actually profit from that). Unfortunately, in most cases this does *not* have a visible impact on the systems performance but in some cases it will really shine. For example the recoding time of a DVD can be reduced by a whopping 33% due to NCQ (if the CPU is not the limiting factor). [...]

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