Disassembling a hard drive

Last modified : 12 June, 2019

In the past year one of the hard drives in my desktop started to fail. It first manifested as SMART errors while booting up, and then one day a remarkably loud scratching noise. The irony is that this was the newer of the 2 hard disks in my RAID1 (mirroring) configuration. It was a Seagate Barracuda ST2000DM001. By my count, it lasted me ~3.5 years. My desktop is usually idle (no gaming, no constant write / read loads) so its a little disappointing given the other soldier in my RAID1 is going strong still. Oh well!

Hard drive bottom Hard drive top

I decided to destructively disassemble the hdd, just for kicks. The following are the pictures I took and short blurbs. I’m glad I did it because its fascinating how such small things can store so much data. The process of disassembly itself was very easy too. All I needed was the correct screwdrivers (I think 3 of them) that any small screwdriver kit would have.

First to come off was the control board. This board plugs into the SATA port on the Motherboard. On the other side it had a 3-pin (I wonder why 3) connection to the motor which rotates the platter and a springy socket for reading the signals coming from the head. I’ve heard there are millions of lines of code running on the microcontroller on the control board. It exports the SATA API and schedules all the accesses on the physical media.

The Control board

The next thing to unscrew was the top plate. There were a bunch of screws (and some hidden under stickers) but once all of them were unscrewed, the top plate came off very easily exposing the inner components.

The inside of an hdd

The next thing I unscrewed were the platters. Again a bunch of screws. What I didn’t quite expect was that the platters were so shiny and thick. I bent them to destroy the data, and I couldn’t with my bare hands. I had to use pliers and good leverage. The surface was shiny like a mirror rather than the rusty brown color of iron oxide that was the color of the magnetic tape of floppy disks. I was also surprised that there were only 2 platters. Somehow I had expected more of them. I’m sure a lot of engineering effort has gone into optimizing the characteristics of these components. I did remember the white paper from Google on Disks for Data Centers (2016). Its a good read if you haven’t so far. I was also hoping I’d see some scratches owing to the loud scratching I had heard, but I wasn’t able to spot any with my eyesight.

The platters which store all data

The next component I took off was the head. It was mounted on a spring system. I probably damaged it while taking it off. The arms were made of solid metal, at the end of which was a triangular plastic protruding with a small sensor at the end. I tried getting good pictures of this from different angles. The base of the arms had a solenoidal loop of wire. I’m guessing the physics of this component are what determine the seek time of these disks.

The head The head The head The head The head The head The head The head

The last thing to come off was the motor. I did note that the bearings were extremely smooth and efficient. I tried incorrectly to uncap the motor at first hitting it repeatedly with a heavy duty hammer before realizing I was going the wrong way. The rotor needs to be pushed out from the bottom of the hard drive towards the top. Even after such excessive abuse, the bearings were more or less smooth-ish. These bearings are probably the majority of the steady state power draw.

The motor

The case itself was pure solid metal. I don’t think any amount of hammering would have bent it. Here’s a picture of the tools that I used:

The tools I used

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