Driving Toward Solid-State Drives

One of the more interesting conversations I had at Microsoft's Windows Hardware Engineering Conference (WinHEC) last week in Los Angeles was with two guys from Samsung. They talked about their company's push into solid-state memory as an enhancement -- and eventually a replacement -- for rotating hard disk storage on computers. Samsung isn't the only manufacturer working to develop plug-compatible flash memory-based storage. In January the five largest drive makers -- Samsung, Seagate, Fujitsu, Toshiba, and Hitachi, formed the Hybrid Hard Drive Alliance to promote the technology. HHD seems to be ready, and the market seems to be primed. The only hold-up seems to the price.The thing that makes solid-state storage for PCs so timely, of course, is Windows Vista, with its support for using flash memory to boost application performance and reduce boot-up times. These technologies, called ReadyBoost, ReadyDrive, and ReadyBoot, can take advantage of several forms of flash -- thumb drives and memory cards, flash on the motherboard, and hard drives that add a flash cache to the rotating storage.

Samsung announced in early March that it had begun shipping samples of its FlashON 2.5-inch drives that combine 80, 120, or 160 gigabytes of rotating storage with 256 Mbytes of flash memory.

Last week in Los Angeles, Andy Higginbotham, director of hybrid hard-drive (HHD) marketing for Samsung, tossed around some very interesting numbers. The goals for HHDs, he said, were to reduce boot times by reading frequently accessed files from fast flash rather than slow disk, and to save power in portable PCs by spinning down the hard disk and doing as much storage I/O as possible from the drive's flash cache.

Early results are positive, he said: boot-ups from HHDs are 30% faster, and the cache extends battery life by about 10%. Hybrid technology also improves the reliability of the hard drive by putting less wear on it. Higginbotham cited a test that showed a drive without embedded flash was spinning 98% of the time and delivered 185 minutes of battery life. With a flash cache enabled, the drive was spinning only 53% of the time -- the other 47% of the time the drive was spun down and the heads parked, a major reliability win -- and battery life increased modestly to 210 minutes. And there's a serendipity, he said -- applications launch about 30% faster.

The growth path is clearly toward more flash on board, but the stumbling block is the cost. The 256-Mbyte cache size on Samsung's FlashON HHDs is "related to bill-of-materials issues," he said -- flash is still more expensive than rotating storage.

But it's getting cheaper very quickly. That was the message of Jim Elliott, Samsung's director of flash marketing. NAND flash density is doubling every year, he said, and prices fall by 50% -- what's $10 a gigabyte this year will cost only $2 a gigabyte by 2010.

This falling price curve means that flash is becoming competitive for more and more applications. Solid-state drives -- hard-drive replacements that pack 30 gigabytes or more of flash into a case that fits in a notebook PC's drive bay -- are appearing on the market. They're expensive, Elliott admitted, but even at $10 a gigabyte, he said, you can justify an SSD for a business notebook on the basis of reliability and reduced drive failure rates. Business notebooks don't need huge hard drives -- 60-Gbytes is adequate -- and with drive failures running 5% to 8% of units a year, the cost of recovering from a crashed drive and validate the decision to spend more for an SSD.

On the horizon, as flash prices fall, Elliott said, a similar TCO argument will be made for SSDs in the server space. Flash uses much less power, which means servers would generate less heat, and could be installed more densely -- a trend that would match the growth in blade servers, for example.

The same arguments will eventually apply in the consumer marketplace, according to Elliott. But my guess is that's going to be more than a few years away. Price rules, and the differential between hard drives and flash is still too great. But the rapid drop in thumb drive prices and their adoption as an everyday tool by PC users gives us a glimpse of what the future holds for flash storage on PCs. For Higginbotham and Elliott, it's going to be an era of "if you build it, they will come."