Micron’s Trojan Horse: The SSD

Micron plans to add PCI Express capabilities to the Virtensys appliance it acquired in January, as the company continues to push solid-state disk (SSD) drives into the data center.

Ed Doller, the vice president and general manager of enterprise SSDs, told analysts on Aug. 8 that Micron sees SSDs creeping back into servers as a sort of Trojan horse: providing a lightning-fast cache for frequently-used data, but—as capacity scales up—perhaps displacing some storage functions as well.

Newer high-performance, high-capacity drives that use the PCI Express interface will provide an alternative to traditional NAS or SAN arrays, Doller added, slowing the trend of moving direct-attached storage outside the server. Micron sees the market for PCIe SSDs increasing by 33 percent (CAGR) between now and 2016, with growth in the SAS interface increasing by about 36 percent.

“I think this new movement isn’t necessarily going to move storage back in, but it will challenge the conventional OEMs for value,” Doller added.

In general, Micron estimates its combined SSD market share (i.e., between enterprise and consumer units) at about 10 percent. It competes with large flash vendors such as Intel, of course, but also specialized enterprise vendors along the lines of STEC—which recently sucked away Gary Gentry, the former general manager of Micron’s enterprise SSD business, as head of Seagate’s SSD business.

Manufacturers of traditional magnetic storage have spent decades refining its processes and increasing its value, and the medium still represents the best mix of price and performance for most computing applications. But as performance becomes more of a priority, SSDs become more attractive: Micron’s new 320H drive offers random read performance above 800,000 iOPs, and random writes above 200,000 iOPs.

As SSDs continue to push forward into new process technologies, the price will continue to drop, making the format more competitive. The main issue, according to analysts and industry-watchers, is that NAND scaling continues to be difficult.

“It’s not as though things are going in the right direction as Flash scales,” noted Steve Leibson of Cadence Design in a recent commentary. “Well, some things actually are going in the right direction: cell size and cost/bit for example. But characteristics such as endurance, retention time, and error rate are not getting better. They’re getting worse with each new NAND Flash generation.”

Manufacturers, he added, “compensate for these increasingly troublesome failings with more and better error correction and managed Flash arrays that allow us to defy the ravages of scaling.”

The black magic there is the flash controller—the logic that discovers and isolates faulty NAND flash cells, so that the drive itself doesn’t fail. Micron uses third-party controllers in its low-end devices while manufacturing its enterprise controllers itself, using on-device logic to manage the drive rather than using the host blade or server to control it.

According to Doller, Micron chooses to use its own flash memory so that it “knows” its capabilities and tolerances. Some competitors are less vertically integrated, and buy the flash memory itself from third parties. Those that do must loosen their design tolerances, he said.

Micron recently acquired Virtensys because of the latter’s capabilities in virtualized storage, similar in concept to the just-announced Fusion-io ION technology. Virtensys provides another avenue into the data center, where storage can be partitioned wherever it needs to be shared. “Instead of placing the same database on each server, what happens if you share that same database on each appliance? Doller asked.

Micron will place a P328, PCIe-based card within the Virtensys appliance, with production scheduled to begin next year. The new version of the appliance is currently being tested with a small number of customers.


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