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Everspin Technologies nvNITRO ST-MRAM SSDs ready to ship

Everspin's new ST-MRAM-based nvNITRO Storage Accelerator pledges 'DRAM-like' performance, but analysts say the high price could limit the SSD's use cases.

Everspin Technologies is close to completing its first move into solid-state drives.

Everspin recently started taking orders for solid-state drives (SSDs) that use spin-torque magnetoresistive random access memory (ST-MRAM) technology. The nvNITRO Storage Accelerator SSDs can deliver ultrafast performance far in excess of NAND flash and approaching DRAM's speed, although it costs more than DRAM.

Industry analysts said the new ST-MRAM-based PCI Express (PCIe) SSDs -- due to ship in late 2017 -- will be relegated to niche use cases until the cost comes down. Pricing for Everspin's nvNITRO Storage Accelerator line starts at $2,200 for the 1 GB SSD.

The nvNITRO SSD uses nonvolatile 256 Mb DDR3 ST-MRAM technology that Everspin Technologies produces with partner GlobalFoundries. Each nvNITRO Storage Accelerator card has 36 of the 256 Mb ST-MRAM devices that went into production in March and will become generally available in the fourth quarter.

"To be a mega-market like some of the mainstream memories, MRAM has to be cheaper than DRAM," said Greg Wong, founder and principal analyst at Forward Insights. "Right now, the performance is worse than DRAM, but it's more expensive. So the only reason you would pay for it is because it's nonvolatile."

Wong said it's hard to envision huge uptake of the new nvNITRO SSDs, "but that doesn't mean there's zero uptake. There are going to be applications that require that speed and persistence."

Everspin Storage Accelerator
Everspin Technologies nvNITRO Storage Accelerator with ST-MRAM technology.

Potential alternative to battery-based SRAM, DRAM

Analysts said Everspin's ST-MRAM could draw the attention of storage system builders seeking an alternative to battery-backed DRAM or SRAM and supercapacitor-equipped SSDs and nonvolatile dual in-line memory modules (NVDIMMs) to protect data in the event of a power loss. Unlike DRAM and static RAM (SRAM), nonvolatile MRAM does not require a continuous power source to retain data or system program code.

Patrick Patla, senior vice president of marketing at Everspin Technologies, said the ST-MRAM-based nvNITRO SSDs could be used "anywhere you want to have DRAM-like performance with the persistence of nonvolatile memory."

The memory chip industry is littered with broken promises and long delays.
Tim Stammerssenior analyst, 451 Research

These use cases include online transaction processing log caches, high-frequency trading applications and storage fabric acceleration. He listed flash storage array vendors and financial traders as potential customers.

"It's really going to have the most benefit for anybody trying to eke out that last 5% to 10% of performance in a tuned system," Patla said.

The first ST-MRAM-based drives are half-height, half-length and U.2 form factors at capacities of 1 GB or 2 GB, and they support block- and byte-level access. The SSDs plug into a computer's PCIe bus and support the nonvolatile memory express host controller interface and storage protocol to reduce latency and boost performance.

Higher performance than Optane SSDs

Everspin's testing showed the nvNITRO SSDs can supply 1.5 million IOPS with 4K block workloads and six-microsecond end-to-end latency. Patla said open source Storage Performance Development Kit drivers for Linux can drive latency even lower. He said the nvNITRO SSDs would deliver an "order of magnitude" difference in performance and predictable low latency not only over NAND flash SSDs but also over faster new Optane SSDs based on 3D XPoint technology from Intel and Micron.

George Crump, founder and president at Storage Switzerland, said storage system vendors can use nvNITRO SSDs in arrays with tiering capabilities. The Everspin nvNITRO SSDs would become the fastest tier with slower NAND flash as the second tier.

"The cost is not going to be inexpensive, but adding a couple thousand dollars to the cost of a Tegile box or a Tintri box is nothing," Crump said. "If by doing that you instantly go from 400,000 IOPS to a 1.5 million IOPS unit -- assuming all those numbers work out -- that becomes a pretty interesting deal."

Higher densities due in future

Patla said Everspin's 1 Gigabit DDR4 ST-MRAM technology -- due in 2018 -- would enable higher capacities of 4 GB, 8 GB or 16 GB in future nvNITRO accelerator cards. Those higher-capacity cards would extend the market to workloads such as RAID arrays. Everspin recently began sampling the 1 Gb ST-MRAM, which Patla said uses a slightly higher performing DDR4-compatible interface.

"The most important thing is that they're moving into higher densities so they're going to be able to drive the costs down to make [MRAM] attractive to a broader range of applications," said Jim Handy, general director and semiconductor analyst at Objective Analysis. "It was mostly used in industrial systems, and now it's going to start being used in storage arrays as a journal."

Handy said Everspin is far ahead of other MRAM manufacturers, but it may take more than a decade for the price of ST-MRAM to drop below DRAM. In the meantime, Handy said it would be "a very natural move" for Everspin to add NVDIMMs at some point, since the company already supports the DDR3 interface and has DDR4 parts in the works. NVDIMMs plug directly into a server's memory channel and offer lower latency than PCIe SSDs, Handy noted.

Will more vendors follow down MRAM path?

Everspin's original devices used a form of MRAM known as toggle to apply a magnetic field to the chip and change the state of the bit. The company shifted to in-plane ST-MRAM with its 64-megabit DDR3 unit that became generally available in 2015. ST-MRAM manipulates the spin of electrons with a polarizing current to reach a desired magnetic state and write bits to memory. Everspin's latest 256 Mb and 1 Gb ST-MRAM devices use perpendicular magnetic tunnel junction (pMTJ) technology, with lower switching currents, to enable smaller bits and transistors, reduced power, higher density and, ultimately, lower cost per bit.

"The implication is that [pMTJ] is the secret sauce that is allowing them to increase the size of the spin-torque MRAM chips really quickly," said Tim Stammers, a senior analyst at 451 Research.

Stammers said Avalanche Technology and big chipmakers such as Samsung, Taiwan Semiconductor Manufacturing Corp. and United Microelectronic Corp. reportedly plan to offer ST-MRAM next year, making "it look like Everspin was right and MRAM does have a future."

But Stammers added a caveat: "The memory chip industry is littered with broken promises and long delays. They're always saying, 'We're going to start next year,' and it never happens."

Everspin Technologies claims to have shipped more than 70 million MRAM raw devices over the last eight years to customers spanning industries such as transportation, automotive manufacturing and enterprise storage. The Chandler, Ariz., vendor went public last year and reported revenue of $27.1 million for the 2016 fiscal year, compared to $26.5 million in 2015. Last month, Everspin posted second-quarter earnings of $8.9 million, an increase of $2.2 million over the second quarter in 2016.

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