Hard Disk? Solid State? A Guide to Hard Drives.

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(Last Updated On: November 8, 2016)

The new MacBook Pro was announced in October to incredible media attention. Praise and derision from all sides became the norm, but one feature went completely uncommented. This line of professional-grade laptops is equipped with solid-state drives. It seems like recent history when solid-state drives (or SSDs) were treated with scorn, relegated to cheap electronics and knockoffs. Real technology, it was said, kept data on hard-disk drives (or HDD). But what’s the difference? And why are SSDs okay now?

SSD vs HDD, new and old technology

SSD vs HDD, new and old technology

First, I need to simplify things (to a horrifying extent, for some) by saying that data is stored as 1s and 0s. The first computers used punch cards to store data; think an index card with holes in it. A space with a hole was a 1, a space without a hole was a 0. Each space is called a “bit,” and if you have a card with, say, ten rows of eight spaces each, that card can store 80 bits. Eight bits make up one “byte” so you can also say it stores 10 bytes. Now, a byte isn’t much; to encode a letter of the alphabet takes 1 byte (a combination string of eight 0s or 1s) so the most data a 10-byte card could hold is the word “mozzarella” or “prosciutto” (I just ate Italian). As computing speeds got faster and faster, new forms of storage were needed, capable of holding many more 1s and 0s. Essentially, the 1s and 0s had to get smaller.


Inside of a hard-disk drive (HDD) is, unsurprisingly, a hard disk. This disk is actually composed of extremely tiny magnetic spaces that can either have polarity in one direction or another. An arm moving over the disk as it spins reads the spaces as being in a certain direction (a 0) or another direction (a 1). By spinning the disk at a blindingly fast rate and moving the arm over it just as quickly, a hard-disk drive can read an impressive amount of data in less than a second. Modern HDDs found in most desktop computers are at least 1 terabyte (1000 gigabytes).


This has disadvantages, of course. To be as fast and accurate as possible, the head of the arm must be as close as possible to the surface of the disk. The heads of modern hard-disk drives can be 10nm from the surface, 1/750000 of the diameter of a human hair! In a desktop, this is okay. But in a portable device, like a laptop or iPod, this gets dangerous. A bump or drop while the disk is being read will push the arm into the spinning disk. At 7200 revolutions-per-minute, this can completely destroy the whole thing, causing you to lose all your data! There’s also an issue with max speed. The HDD speed is limited by the speed of the disk and the speed of the arm, both of which are limited by…well…physics. Spin too fast and the disc can literally melt due to friction.

Solid-state drives, on the other hand, have no moving parts. It’s the same technology used in thumb drives, but optimized to be much faster and hold vast amounts of data. The technology has been around for years, but has been prohibitively expensive until recently. SSDs are smaller, use less power, and can supply more data in less time than HDDs. You can drop one and it keeps chugging along. By mounting the SSD to the motherboard, load speeds practically disappear, allowing a computer to boot-up within seconds. This is called PCIe, and is featured on the new MacBook Pro. This has allowed solid-state drives, previously relegated to small electronics such as cellphones and MP3 players, to be featured as the main hard drive on powerful computers.


For decades, hard-disk drives ruled the computer world, but it’s just updated dated technology. Heck, even the first few generations of iPod used hard-disk drives. Manufacturers tried to innovate by making smaller, faster drivers with more storage but the same limitations held them back. The move by large consumer-tech companies to feature SSDs will lead to the same innovation. We’re betting on seeing tiny terabyte chips in cellphones within a decade or so. If you’re interested in upgrading your computer to an SSD drive, contact your local iFixYouri or leave a comment below. Our technicians will be more than happy to help.