|AS SOLID-STATE STORAGE enters its adolescence, the technology is still trying to find its place in the storage food chain. Solid state, or flash, is becoming more familiar and widely available as it continues to develop into distinct market segments, but questions remain about power consumption, performance and the best uses for solid-state drives (SSDs).
Framingham, MA-based IDC tried to quantify some of the uncertainty in a recent benchmarking report that compared SSDs, hard disk drives (HDDs) and hybrid drives using a laptop PC. Dave Reinsel, lead author of the report and group VP of storage and semiconductor research at IDC, says they found that drive performance can vary greatly from device to system level. "The system can act as a great equalizer and diminish some of the benefits that you might have seen at the device level," he says. IDC's report also concluded that SSD and hybrid technology use will continue to grow, and that SSD controllers will be a key piece of further development.
As SSDs mature, key differences are emerging. Single-level cell (SLC) vs. multi-level cell (MLC) flash is one distinction. Steve Swenson, product strategy and innovation manager at SSD maker Imation, says that early next year the firm will launch MLC-based flash, which stores more bits per cell and costs less to make. "It's where solid state needs to go to get to reasonable price points," he says.
Josh Tinker, market development manager, personal compute at Seagate, points out that enterprise-class vs. consumer or PC-class flash drives will continue to diverge. "You'll see more and more of a difference," says Tinker, adding that enterprises will probably lean toward creating a tier of SSDs, while small amounts of flash in hybrid-type drives might be a better fit for consumer use.
Even the term flash, used to describe different kinds of SSDs, may be on its way out. Jamon Bowen, financial industry account executive at Texas Memory Systems, which makes DRAM arrays, points out that NAND flash and DRAM flash are commonly confused. "There's a clear line," he says. "They're probably going to have to come up with a new acronym to separate it out."
SSD prices are dropping, but cost remains a concern. Odyssey Logistics & Technology Corp., a transportation management services provider in Danbury, CT, justified the higher price of a Texas Memory Systems DRAM array to meet service-level agreements during its busy summer season. Database administrator Eric Brown cites customer wait times a quarter of what they were last year, and Brad Massey, director of IT support services, says "we have happy users because there's no system latency visible to them."
At solid-state maker Fusion-io, CTO Dave Flynn says comparing SSD and HDD cost and power consumption can be misleading. Instead of single component comparisons, he says, compare arrays providing equivalent performance. "A single SSD and a single HDD aren't necessarily that different in power consumption," he says. "The real question is how much computing is done per watt."
IDC also tested hybrid drives, which use a small amount of flash memory as cache on a hard drive. Tinker notes that Seagate's first generation of hybrid drives "didn't bring enough benefit to command the premium we needed to ask." Seagate plans a second-generation release, but Tinker sees hybrid drive traction mostly in laptops for now.
Reinsel says the jury's still out regarding hybrid drives. "The question is 'How do you leverage a hybrid hard drive in an enterprise environment?'" he says. "Because they already use huge caches many times to help accelerate performance." Swenson adds that hybrid is only "a transitional technology."
However the flash market continues to develop, solid-state or hybrid drive use will depend heavily on existing storage infrastructures. "One of the big things is that system OEMs are going to have to design around the specific technology to extract all the benefits," says Reinsel.