Picking a hard drive used to be fairly easy, you'd get the biggest one you could afford. And possibly pick from one of two speeds: 5,400 RPM and 7,200 RPM (although faster and slower speeds are available).
These days things are a lot more complex. New SSD (solid-state drives) sit alongside HDD drives and thanks to falling prices they're no longer an expensive rarity for rich business execs and computer fanatics.
Tech companies have also figured out how to combine SSD technology with traditional HDD technology to create hybrid drives with the best of both worlds. Apple has one of these called the Fusion Drive.
On top of that hard drives are sold in a myriad of different sizes, ranging from 3.5in to 2.5in for laptops, and even 1.8in for smaller devices. On some Apple products the hard drive can be replaced, on others it's welded onto the circuit board. Meanwhile external options are available and Apple's new Thunderbolt technology is so fast that it can keep up with any of the latest, fastest hard drives.
When it comes to hard drives it's a minefield out there. This feature will help you understand and choose the right drive:
How does a HDD drive work
A traditional hard drive works pretty much like a miniaturized record player. Imagine the record is coated in a metal that can be magnetized: that's the disk called the 'platter' and it spins around. The magnetic material enables it to store data (0s and 1s) as magnetized 'on' or 'off' blocks. Above the platter is an arm called the 'actuator' that reads these magnetized blocks as binary code (0s and 1s) or writes to the disk by setting the magnetic blocks on or off.
The faster the platter spins the quicker the hard drive works, which is why it's measured in RPM (revs per minute) like a car. But the actuator has to be able to keep up with the speed, which is why they've got better over time.
There's two ways of making the hard drive bigger, to have a bigger platter or to create smaller blocks of data on the platter. Both have happened over time which is why there are different hard drive sizes and units have become smaller over time.
What's so good about HDD
The great thing about traditional hard drive technology is that it's cheap. You can pick up this 1TB 2.5in hard drive from Amazon for just £54. That's just 5p per GB, a ridiculously cheap amount compared to SSD drives (or even hard drives from years gone by).
Compare this to the popular Crucial M4 SSD which costs £130 for 256GB. That's almost 50p per GB, or 10 times as much. Given that an SSD costs ten times as much as a HDD you'd expect it to deliver something pretty special, right? The good news is that it does.
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