We tear apart a hard drive and SSD to show you how they work

What's inside your PC's storage? Glad you asked.

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Credit: Mike Homnick
It's what's inside that counts

It’s the day everybody dreads: You power up your PC and it sits dormant, failing to boot because your hard drive or SSD is dead. But after you stop cursing and reaching for your backups—you do create backups regularly, right?—you might as well make the best of things.

There’s a world of small wonders hidden inside every storage drive if you take the time to dig around. Since storage drives die far less frequently than they used to, the opportunities for dissection are rare. So we’ve broken out our screwdrivers and dissected both a solid-state drive and a traditional hard drive for you, to reveal what makes them metaphorically tick. If your drives start actually ticking, back up your data now and start looking for a new one pronto.

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Credit: Thomas Ryan
Inner knowledge

Let’s start with a traditional hard drive.

Here’s a look at the key technology inside a Western Digital HDD: three magnetic platters that spin at 7,200RPM when the drive is powered on. Each plate offers about 80GB of storage, for a total capacity of 240GB in this particular model.

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Credit: Thomas Ryan
Popping the top

Using our handy screwdriver and Torx bit, we removed the cover plate from our dead hard drive. In the upper-left corner you can see the mechanism that controls the position of the magnetic read head that’s floating over the disk platter near the center of the image. This arm moves around to read or write data to different places on the disk.

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Credit: Thomas Ryan

Shifting to a different angle reveals the orange ribbon cable that connects the mechanical portion of the drive to the controller chip underneath. Look at how smooth and reflective the spinning platters are!

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Credit: Thomas Ryan
Use your heads

Here’s a closer look at a read-and-write head that manages data on the drive. Although we’re only looking at one of the heads in this picture, there’s a separate head for each of the three platters in this drive. These heads fly mere nanometers above the platters as they rotate at 7,200RPM.

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Credit: Thomas Ryan
Logic, captain

Those platters and heads need to be told what to do, of course. Here’s the logic board from our dead hard drive. As you can see, it was manufactured by Foxconn in China. This relatively small board holds a controller chip near the center, and then routes the data out to the SATA connector at its edge. That’s where you insert the SATA cable that connects the hard drive to your motherboard.

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Credit: Thomas Ryan
The brains

The hard drive’s controller chip, made by Marvell, is ready for its close-up. The chip’s a tiny low-power processor that facilitates the seamless transfer of data between the platters and the rest of your PC.

Credit: Thomas Ryan
The sum of its parts

Finally, here’s an overview of the entire family of components that come together to make a hard drive. Four short screws, six long screws, a small PCB, and some monstrous mechanical hardware.

On to the solid-state drive!

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Credit: Thomas Ryan
He's dead, Jim

This particular SSD is an old 128GB OCZ Vertex 4 that gave up the ghost just a few days ago. The large rectangular chips are the NAND flash memory, which Micron manufactured.

Credit: Thomas Ryan
RIP Indilinx

As with hard drives, all SSDs feature a controller chip, which routes the data to the NAND and then back to your PC. The OCZ Vertex 4 relies on an old Indilinx Everest 2 chip that was pretty great circa 2012 thanks to its generous feature set and support for speedy SATA 3.0 connections.

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Credit: Thomas Ryan
Staying connected

Speaking of SATA, here’s the connector. SSDs are tiny enough inside their 2.5-inch form factor enclosures, but seeing one without its housing really highlights how small solid-state drives really are.

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Credit: Thomas Ryan
NAND, meet RAM

Most SSDs use a few hundred megabytes of RAM as a buffer between the NAND and the PC. This drive is no exception, with the RAM chips supplied by Hynix.

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Credit: Thomas Ryan
Deceptively simple

There’s not much to an SSD physically. In fact, you won’t find a single moving part onboard—just chips on a circuit board and a protective enclosure. Combine that with eight short Philips-head screws and years of semi-conductor R&D, and you’ve got  blazing fast performance for your storage system.

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Credit: Thomas Ryan
But wait! There's more

We love ripping things apart here at PCWorld. If you enjoyed this glimpse at the innards of storage, be sure to check out our graphics card, RAM, and motherboard dissections, too. We’ve also taken an in-depth look at the physical design of AMD and Intel processors. Learn something!