SHIFT: Are solid-state drives really better than hard disks?

When Apple rolled out the MacBook Air with its solid-state disk (SSD) inside, it felt like a new era in laptop computing had begun. Are solid-state state drives poised to replace those spinning hard disks we've become accustomed to over the past few decades?

Not so fast. Although there's a transition underway, for all that sexy new technology, you'll pay a whole lot more to be an early adopter. In this case, solid-state drives will cost you at least $1,000 more for a 64GB drive in laptops from Apple, Toshiba or Dell, but offer you less space and sometimes slower speeds than conventional hard drives. I talked with experts and analysts about the latest solid-state drive offerings, trying to find out if the time is right to go for the latest disk tech. Follow the Continue link to read my findings.

Not-So-Solid Specs
Think of the allure of a solid-state drive: It has none of those old-timey moving parts, and it's faster, right? The problem is, in most cases, flash memory is not able to write data as quickly as a conventional hard drive. Jacqui Cheng of Ars Technica found that solid-state write speeds on a MacBook Air were between 13.86 and 14.67MB per second (MB/s), less than half as fast as the 33.3MB/s of a hard drive-equipped MacBook Air with its relatively slow-spinning 4200-RPM disk inside. However, the MacBook Air's solid-state disk was able to read data slightly faster (between 7.29 and 49.59MB/s compared with the spinning drive's speed of 6.32 to 32.74MB/s on that same Macbook Air).

Dave Zavelson, Senior Manager for Precision Mobile Workstations at Dell, also points to the lack of speed advantages of today's solid-state drives, which he's noted on his company's Precision M6300 laptops with an optional 64GB SSD ($1030 additional cost). "You are looking at performance roughly on par with the conventional hard drives. I think you'll probably get a little more performance out of a 7200-RPM hard drive." Well, that's disappointing.

Solid-state drives will get faster as soon as operating system software is optimized for them. Semiconductor analyst Jim Handy of market research firm Objective Analysis says Mac OS X and Windows XP and Vista are designed to take advantage of spinning hard drives, not SSD. "A lot of it has to do with software," Handy says. "The operating system does tons and tons of little tiny writes. If they were able to consolidate those into less frequent writes that were larger, solid-state drives would all of a sudden look enormously better than a hard disk drive."

Hard Truths
What's so bad about old-fashioned hard drives, anyway? They've gotten a bad rap over the past few decades, because when they were first rolled out in the '70s they were excruciatingly fragile. Not any more. In fact, today's hard drives can take 300g of shock when their heads are parked, and can even withstand 50g while they're operating (though SSD can withstand 1,500g whether it's operating or not). All these numbers represent way more force than any human being can survive, and certainly a laptop's screen would shatter long before that harsh 50g shock had been reached.

Solid-state drives are indeed more durable than their hard-drive counterparts, and that's why the U.S. military has been an enthusiastic consumer of SSD for a variety of harsh battlefield conditions, especially in its fighter jets. In an environment where your fillings can be shaken out of your teeth, a hard drive might suffer from all that vibration. Besides ceasing to function at all, this can cause reading delays, something that might be highly inconvenient at supersonic speeds.

SanDisk (the part of SanDisk that used to be M-Systems) has been making huge solid-state drives for the military for more than a decade, and many are so packed with flash memory chips, the drives challenge designers to fit them all inside a normal-sized laptop case. These can be enormously expensive, though. Says analyst Jim Handy, "The highest-priced military laptop I've heard of is $70,000. The military likes stuff like that. They can afford it. It isn't a question of how much you can put in there; it's a question of how much you can pull out of your wallet."

laptop_power_budget.jpgGraphic courtesy Aqeel Mahesri and Vibhore Vardhan

No Spin Zone
Traditional hard drives have also been criticized for their power-hungry nature. While a spinning hard drive drains about five times as much power as a solid-state drive, as you can see in the graphic above, the typical power budget for a laptop only blames that hard disk for 5 to 15% of its power drainage. Dell's Zavelson agrees. "In our power budget for a notebook, a hard drive is a pretty small piece of the overall budget," he told DVICE. "Look at the CPU, the LCD screen, running the graphics, DVDs. If you look at overall battery life, what we are seeing is a pretty small improvement."

My take? Solid-state drives certainly are less power-hungry, are durable, and have speed advantages over conventional hard disks, but until the price of these drives descends significantly, it's not really going to be worth it to spend an extra thousand dollars for their marginal benefits.