How hard is your drive?

Now that the partying and the rush of the holidays is over, thank goodness, everything can turn back to normal.

And normal in my world is defined as in I writing something about anything that contains something technical or wires.
I’m sorry boys and girls, I’m going to continue writing ;-).

As for my first “tech” subject of this year I was thinking about explaining how a hard drive works. We all use it and we don’t really think about how it is working.  But it is rather interesting to know.
It can also help you debug some issues.

A first interesting thing you should know that hard drives are manufactured in “clean rooms”, like an operating room. The slightest particle of dust that makes manages to get it’s way inside the HDA can literally destroy the drives.
This is because the drives (and I’ll explain in a second what I mean by this) rotate at high speed (5400, 7200 and even some 10000 RPM).
Just so you know, when you ever plan to open up your hard drive, you will be unable to use it again.

Now for the components. When you take an average internal hard drive and you flip it over.
You’ll see a, most likely, green circuit board.
This part of the hard drive is in control of everything. The exchange of data with the computer, sending commands to the heads to read or write data, the spinning of the motor, etc…
Let’s not take this too far in detail.

If you open up the hard drive (and please don’t do this, and if you do, don’t blame me for breaking it ;-)).
The drive looks something like this

The big round shiny thing is ofcourse the drive. And a hard drive can have multiple drives actually.
On top of the drive(s) you can see an arm. This contains all the heads, needed to read or write the hard drive. They all move together.
The movement of this arm is also controlled by a little motor. This motor is called a voice coil (don’t ask me why, that’s just what it is called). Depending on the current direction on the coil the arm will move left or right. And depending on the intensity of the current the arm will move more or less.

The data that you are saving is stored as a series of 1s and 0s. And this data is stored in a very organized way. The bits of data are sotred in concentric, circular paths which we call tracks. Each of these tracks is broken up in some smaller areas which are called sectors.
A small part of the hard drive is used to map the sectors that have been used or are still free. This should be rather familiar to you.. In windows this is called the File Allocation Table or… FAT. Ring a bell? ;-)
Whenever you want to store data, the map of the hard drive is check, the arm is moved to the sector which has some free space and the data is written magnetically.

Nice piece of equipment.. is it not?


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