Hard disk drives vs. solid-state drives: Are SSDs finally worth the money?

Computerworld - Three years ago, I wrote a story comparing hard disk drives to solid state drives (SSDs) based on capacity, performance and cost.

A lot has changed in three years. For one, laptops are quickly being eclipsed by tablets, which have NAND flash memory embedded on their motherboards. In addition, operating systems like Windows 7 have been optimized to take advantage of SSD I/O performance.

SSDs today are far more reliable, have greater endurance and perform better (in some cases, two to three times better) than in 2009.

There are also new SSD categories. For example, hybrid drives combine NAND flash cache memory with a spinning disk in a hard-drive form factor. In addition, in adherence to Intel's new ultrabook computer specifications (PDF), manufacturers are beginning to produce laptops with two drive slots, one for a hard drive and the other for a low-capacity cache SSD which works with hard disk drives to speed up boot and application load times.

Perhaps the single biggest change, though, is price. In 2009, SSDs cost around $3 per gigabyte. That meant a 120GB SSD cost you more than $300. If you were paying $700 for a laptop, it wasn't reasonable to expect to pay almost half that for a new drive.

Today, however, SSDs cost close to one-third of what they did in 2009 -- in many cases, less than $1 per gigabyte. For example, Crucial in July announced its new low-cost v4 SSD that costs $100 for a 128GB model and $190 for a 256GB model. This isn't unexpected; in January 2012, research firm IDC predicted that prices of SSDs would tumble this year. (Of course, hard drive prices have also plummeted. These days, you can pick up a 7200rpm, 1TB laptop hard drive for a little more than $100. )

One thing hasn't changed, though: While they may never beat out hard drives in price, SSDs will always have one major advantage: No moving parts. This means no mechanics to break, even when a machine is jostled or dropped. SSDs are natively more resilient than hard drives, particularly when it comes to mobile applications.

A hard disk drive with mechanics vs. a solid state drive with NAND flash chips (source: Intel)

Comparing SSDs and hard drives

As in my 2009 article, I tested an SSD and a popular, well-performing consumer hard drive to see how they rate for performance, cost and general usability: the Intel Solid-State Drive 520 Series (240GB capacity; $275 to $415) and Western Digital's 500GB WD Black (previously called the Scorpio Black), a 7200rpm 2.5-in. hard disk drive with 16MB of DRAM ($112 to $262). I also checked out a hybrid drive: Seagate's Momentus XT Solid State Hybrid Drive (750GB; $195 to $324), which includes a 7200rpm 2.5-in. drive with a SATA 6Gb/s interface. A 500GB version of Momentus sells for as little as $89.99.

(When requesting test units, I asked the companies for their highest-capacity review models. While capacity affects SSD performance, it really doesn't affect hard drive performance -- at least, not until the drive is filled.)

How I tested

For the benchmark tests, I used an Apple MacBook Pro running OS X Mountain Lion, with 8GB of RAM and a 2.3GHz Intel Core i7 processor.

To measure read/write performance, I used the Blackmagic Disk Speed Test. To determine file transfer speeds, I used a 1.19GB folder that held 327 JPG images. The file was transferred from a desktop folder to the hard drive.

Additionally, I tested application load time by opening a 10MB PowerPoint presentation and a 372-page, 300KB Microsoft Word document.

The Intel 520 Series SSD

I started with the Intel 520 Series SSD. According to the specifications from the manufacturer, it had the best performance potential of all three drives I tested.

The SSD was actually tested on two separate platforms: First, I ran the tests described above using my MacBook Pro with an SATA 3.0 internal drive interface. However, because SSDs will perform better right out of the box than after they've been filled with data, I decided to also send the SSD to a professional drive testing service, Calypso Systems, which benchmarks drives for drive vendors and system manufacturers.

(Story continues on next page.)