Giz Explains: SSDs and Why You Wish You Had One

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Speed. Toughness. Efficiency. Silence. That's why we want solid-state drives in our computers. But we worry about the zoom-zoom performance degrading over time, and the fact that SSDs might eventually wear out. Here's what you need to know about 'em.Why Solid-State Drives Are Awesome (Or At Least, Better Than Hard Drives)To understand what's great about SSDs, let's start with HDDs (you know, old-fashioned hard drives). On a basic level, a hard disk drive works thusly: Inside is a magnetized recording surface called a platter that spins around really fast, with a head that zooms across disk to read and write data—think kinda like a record player, except the head never touches the surface, 'cause that would be very, very bad. So, you can see the problem with hard drives: They're fragile (don't drop your computer) and they're slow to access stuff because the head has to physically move to where the data is.



With an SSD, on the other hand, we're talking straight silicon. What's inside is a bunch of flash memory chips and a controller running the show. There are no moving parts, so an SSD doesn't need to start spinning, doesn't need to physically hunt data scattered across the drive and doesn't make a whirrrrr. The result is that it's crazy faster than a regular hard drive in nearly every way, so you have insanely quick boot times (an old video, but it stands), application launches, random writes and almost every other measure of drive performance (writing large files excepted). For a frame of reference, General Manager of SanDisk's SSD group, Doron Myersdorf, says an equivalent hard drive would have to spin at almost 40,000rpm to match an SSD. And, you can drop it—at least, a little.Secrets of the SSDTypically, what you've inside an SSD is a bunch of NAND flash memory chips for storage—the same stuff found in memory cards and USB thumb drives—along with a small cache of DRAM, like you'd find on most current hard drives. The DRAM is also flash memory, but the difference between the two is that the storage memory is non-volatile, meaning the data it holds won't go poof when it loses power, while the faster DRAM is volatile memory, so "poof" is exactly what happens to DRAM data when the power goes out. That's fine because it's the faster DRAM is just for caching things, holding them temporarily to make the whole system work faster.

So, let's talk a bit about flash memory itself. I'll try to keep it straightforward and not lose you, because it's key to the benefits and problems with solid-state storage.

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