Solid-state storage earned a hot technology's badge of honour - a backlash - at the Diskcon conference in Santa Clara, California.
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, 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.
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. Bullshit. It's not," Workman told attendees. "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 emphasised 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 organisations are working on these standards, she said.
A deal that Smart announced 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 specialised product, Omura believes.
SLC flash stores only one bit per cell, so it packs less capacity into a given space. But this type is used on enterprise products because it's better-suited to both reading and writing data, and less prone to flaws that can reduce a chip's capacity over time. SandForce's controllers are designed to manage MLC chips so they last longer. Smart will use the SandForce controllers in enterprise SSDs built with its MLC flash chips.
Enterprises may eventually embrace MLC flash, especially in products such as midpriced x86 servers, where buyers concentrate on price, said TrendFocus analyst John Chen, who spoke at Diskcon. But the controller's ability to prevent chip degradation will be key to flash storage, he added. "I think it's all about the controller," Chen said. SandForce isn't alone in trying to leverage low-cost MLC silicon, with bigger vendors such as Marvell developing such controllers too, he said.
The next big step will be for more vendors to qualify their flash storage products for enterprise environments, a process that should bear fruit next year, Chen said.
Despite these technical concerns, next year should be a big one for enterprise flash. Most of the major enterprise storage vendors have put flash offerings on the market this year, and the partnership announced last year between Intel and Hitachi Global Storage Technologies is on track to deliver its first products in the first half of next year, said Dean Amini, director of enterprise product marketing at Hitachi GST. Intel already sells flash silicon for enterprise storage.
The companies plan to make flash products, in HDD form factors, that match the performance of Fibre Channel HDDs under any type of workload, according to Amini. A slide of technical goals showed they plan to offer advanced power management and MTBF (mean time between failures) of 2 million hours.
The enterprise flash business is in such an early stage that the dominant provider of chips, STEC, even welcomes competitors.
"The industry and the market is growing rapidly ... and I think adding another credible vendor, somebody that can pass the qualifications, will just increase the market even more," said Scott Stetzer, STEC's director of marketing for enterprise SSD products.