Solid-state storage earned a hot technology's badge of honor -- a backlash -- on Wednesday at the Diskcon conference in Santa Clara, Calif.
Storage components based on NAND flash chips have recently been promoted as an alternative to spinning HDDs (hard disk drives) in netbooks, laptops, servers, and enterprise storage platforms. Flash advocates claim they offer higher performance and greater reliability because there are no moving parts. But on Wednesday, even companies that are selling flash-based products cautioned that certain benefits may come only for certain applications or aren't here yet at all.
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It's "stupid" to use SSDs in a network-attached storage device that overwrites a large amount of data over and over, because of the tendency of flash chips to wear out every time data is written to them, said Mike Workman, chairman and CEO of storage equipment maker Pillar Data Systems.
Workman, who helped create IBM's storage business, believes good engineering will eventually overcome flash's limitations but complained that the market today is consumed by hyperbole.
"One of the claims is that because the SSD's solid-state, it's more reliable," Workman told attendees. "It's not. I'll tell you right now, the data that I have in the lab, it should make the solid-state guys be embarrassed," he said.
"The solid-state guys'll win," Workman said. "But they're not there yet."
Workman's company didn't come to the conference as a rival to flash vendors. Pillar already offers flash options on its storage platforms. But Workman emphasized that the new technology is just one component of an overall enterprise storage strategy.
An executive of another seller of SSDs, flash chip vendor Smart Modular Technologies, issued her own caveats about them. Flash chips deliver spectacular performance while in a "virgin" state, when the first bits are being written to them, but their write speed falls off dramatically within hours, as new bits are written over on the same silicon, said Esther Spanjer, Smart's director of SSD technical marketing. This is a normal occurrence, but some testers have tested chips in the virgin state, giving unrealistic results. Likewise, an SSD may need time to adapt after switching from sequential to random tasks. An ideal test would take it through that process, she said.
Today, makers of flash silicon may test their products with any combination of tasks and configurations, because there are no standard benchmarks, she said.
"Things are pretty much all over the map, and it can be very confusing" for makers of storage platforms that want to use flash in them, Spanjer said. The Storage Networking Industry Association and other organizations are working on these standards, she said.
A deal that Smart announced on Tuesday marked a breakthrough for a new approach to flash storage. The company agreed to buy flash controllers from SandForce, which claims it has the technology to make flash price-competitive for a wide range of enterprise uses. Its controllers manage MLC (multilevel cell) flash, the high-volume, relatively inexpensive type used in consumer products such as portable media players.
Thad Omura, SandForce's vice president of marketing, told the conference that only MLC flash can compete with HDDs on cost. Most enterprise products today use SLC (single-level cell) flash, which will never fall to the needed price levels because it's a specialized product, Omura believes.