Solid state drives have no moving parts and use silicon chips to store information, making them more durable than a traditional hard drive. The thin black rectangles on the solid state drive circuitboard to the left side of the picture are the solid state drive's memory chips. (Courtesy Toshiba)

A traditional hard drive has a delicate read/write head on an arm that moves across a spinning platter, as seen in this cutaway view of a hard disk. (Courtesy Seagate)

Compact and durable solid-state hard drives were once reserved for demanding groups with big-budgets, such as the military, but that is changing. Prices are tumbling and they're starting to carve out a respectable niche for themselves in the mobile world of the average consumer.

Solid-state drives (SSDs) store information on memory chips instead of a spinning disc. The technology isn't new, but storage capacities have traditionally been fairly limited and SSDs have been extremely pricey compared to regular hard drives.

No more.

As the cost of memory chips has fallen in recent months and storage capacities have risen, SSDs have become increasingly popular for gadgets such as digital audio players that only require a few gigabytes of storage space. Solid-state technology is especially appreciated by people who use media players on the go, such as joggers and fitness buffs — anyone who enjoys an active lifestyle — because it doesn't skip and it's hard to break.

And now that it's becoming more economical to build solid-state drives with multi-gigabyte capacities, they're starting to move beyond handheld gear.

SSDs — also referred to as flash hard drives — are still by no means cheap, retailing for hundreds of dollars more than a comparable hard drive, so it's going to be a while before they become a common sight on the average computer store's shelves.

But the rising capacity and falling price of SSDs, along with the fact that they 're more durable and consume less power than traditional hard drives, have suddenly made solid-state drives a viable high-end option for computer makers — particularly for notebooks.

How it works

The biggest difference between solid state and "traditional" notebook drives is that solid-state drives contain no high-precision moving parts that can be damaged or wear out. A hard drive, in contrast, has platters with data on them that are spun around by a motor while a delicate read-write head moves across the surface of the disc (think of the way a record player's tone-arm moves across a spinning vinyl LP).

A solid-state drive is basically a computer memory chip, or a group of chips linked on a circuitboard. Each chip has billions of memory cells that can be turned on or off via an electrical charge to represent the zeroes and ones of binary information — the "language" computers speak to run programs and store information.

The lack of moving parts not only results in a quieter machine, it also reduces the risk of hard-drive failures, explains Darren Leroux, computer maker Hewlett-Packard's product marketing manager for consumer notebooks. If you drop a hard drive, there's a good chance the delicate drive mechanism will be wrecked, for example, but an SSD can sustains falls and bumps without experiencing any ill effects.

"They [SSDs] are a lot more durable … they're more rugged or tough," than a traditional hard drive, Leroux says. "If you drop your notebook the [read-write] head's not going to crash into the platter and compromise your hard drive, because it [an SSD] is basically just a chip with data stored on it."

Boosting performance

The lack of a motor slashes an SSD's power consumption by about 50 per cent compared to a traditional hard drive. The drive is only one of the components drawing power in a notebook, but replacing a laptop's hard drive with an SSD generally increases battery life by about 10 per cent.

In real terms, this translates to around 20 to 30 additional minutes of run time from a standard notebook battery, according to Doreet Oren, the SSD director of product marketing for memory manufacturer SanDisk.

Solid state technology also outperforms traditional hard drives when it comes to speed, at least for reading data.

"It's very fast to boot up, it's very quick to come out of standby, and it's very quick to launch applications," says Leroux, talking about laptops that use an SSD instead of a hard drive.

According to HP's own comparisons, SSDs generally offer a 30 per cent performance increase over a platter-based hard drive. There's a caveat, though. Leroux is quick to point out that flash drives are only faster in terms of reading the data stored on their memory chips — when writing data (saving it to the drive), users will actually see increased latency ranging from a few milliseconds to a few seconds because writing to flash memory is generally a bit slower than writing to a high-performance hard drive.

"You're able to multitask and write multiple things at once on a hard drive, whereas solid state might have some issues in terms of trying to do multiple saves at once," he says.

Slowly gaining ground

For years, SanDisk has sold high-capacity solid-state hard drives to the military and other institutions that were willing to pay a high price in exchange for the performance and reliability the drives offered.

The turning point came at the 2007 Consumer Electronics Show (CES), where SanDisk announced its first solid-state hard drive specifically tailored for the consumer market. The drive's 32 GB capacity, according to Oren, represented what is considered a sweet spot in the market, combining an attractive capacity with a reasonable price that allowed manufacturers to start courting the consumer market.

Since that unveiling last year, SanDisk has been joined by other companies in its consumer push for memory-based storage. Computer manufacturers, including Dell, Lenovo and HP, have been researching the technology for years, but have now reached the point where they consider it cost-effective to start using it in consumer-oriented products.

HP, for example, made solid state available in some of its high-end and ultra-portable business notebooks as of November 2007, but only as a configure-to-order option from direct sales representatives. Apple's MacBook Air ultraportable notebook, announced in January, offers users the option of ordering a 64GB solid-state hard drive instead of the 80 GB traditional hard drive.

Obstacles to overcome

While SSDs have obvious benefits, the biggest barriers to widespread adoption of solid state are still price and capacity.

Presently, consumers can expect to pay a premium of about $1,000 to swap in a solid-state hard drive to their notebook, meaning the option is initially geared mainly towards well-heeled corporate business users. These highly mobile customers, willing to trade price for peace of mind, are the traditional early adopters of new portable technologies.

But with these corporate road warriors trail-blazing for solid state, the expectation is that it will increase demand and drive prices down, making SSDs accessible to an ever-widening pool of everyday consumers — much like the evolution of smartphone and cellphone technology.

Capacity, however, remains a stumbling block. Traditional notebook hard drives typically offer capacities of between 100 GB and 250GB for a tenth of the price of a much lower-capacity SSD. A year after SanDisk announced its 32GB drive at CES the standard capacity of solid-state drives has already doubled to 64GB, but it's still far short of the mark set by hard drives. "With the big buzz around Vista, a 32GB drive really doesn't make sense because the majority of that hard drive space will be eaten up by the operating system itself," Lenovo spokesperson Eric Chong points out.

But in a business environment where users aren't generally allowed to store a lot of personal data, movies or games on company-issued notebooks, the smaller capacity of SSDs is sufficient for daily tasks, and issues such as increased durability, data security and notebook battery life are more important considerations for many users.

Looking to the future

On Feb. 26, 2008, Lenovo offered one of the first notebooks to incorporate solid state — the ThinkPad X300, which ships with a 64GB solid state drive for $2,799.

Market watchers say we can expect more manufacturers to follow suit and start rolling out notebooks with solid state offered as the standard drive instead of an optional upgrade — a convention that will soon start to have an impact on the design of the notebooks themselves.

Today, notebooks are designed with space for standard 2.5-inch hard drives. As SSDs become more common, expect to see smaller notebooks designed around the more streamlined 1.8-inch drives.

"When you're dealing with a sub-notebook, every quarter inch or millimetre will make a difference, so absolutely [solid state] will affect design," Chong says.

Chong is confident that solid state will eventually replace hard drives, at least in notebooks. As prices drop and capacity increases (by the end of the year, the capacity of consumer-oriented drives should double again to 128 GB), Leroux predicts sales will increase by as much as 20 per cent in the next three or four years.

Nevertheless, traditional hard drives with their far greater capacities won't be going away any time soon. Oren predicts the motor-driven hard drive will hold on to markets where large amounts of data need to be stored — such as in servers, back-up systems, high-definition movie players and media storage devices — while solid state gradually becomes the norm for portable devices.

"Until there's a very big, broad mass market for solid state hard drives in notebooks, we won't see the prices drop," adds Leroux. "But we will see capacity increase exponentially over the years. Probably in about three years time we'll see a capacity of about 260 GB for a solid-state drive, and we'll see the price drop not quite to parity [with traditional hard drives] but pretty close to that."

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