Toshiba, Micron push technology envelope at Flash Memory Summit

Article By : Rick Merritt

Micron revealed performance data of working SSDs based on 3D XPoint memory, while rival Toshiba showed progress on conventional NAND flash.

On the first day of the Flash Memory Summit held in Santa Clara, California, Micron revealed its performance data of working solid-state drives based on 3D XPoint memory.

Separately, rival Toshiba showed progress on conventional NAND flash, and mega-customer Facebook called for multiple new kinds of memory products.

A Micron engineer showed prototype SSDs with Xpoint memory chips on a PCIe Gen 3 interface handling writes at less than 20 microseconds and reads and less than 10 ms, ten times faster than existing NAND SSDs. Devices using four PCIe channels delivered up to 900,000 I/O operations per second. SSDs using eight lane PCIe peaked at 1.9 million IOPs.

__Figure 1:__ *Micron’s Quantx SSDs sport ten times faster response rates than today’s NAND SSDs. (Image source: Micron)*

Overall, Micron promised the drives it will brand as Quantx will deliver four times the capacity of DRAM. Compared to NAND it will offer ten times lower latency and 10x higher IOPS at up to 32 queues.

The company showed data on Xpoint SSDs at densities from 200 to 1600 Gbytes. However, it did not announce availability or pricing for the drives or the chips based on them.

The results amount to some of the first specific proof points for the technology Intel and Micron announced a year ago. A Micron executive reinforced the companies’ position that XPoint will not replace NAND but fill a gap between DRAM and NAND in performance, capacity and price.

Facebook is among a handful of potential customers testing XPoint products. In a brief interview with EE Times, a keynoter from Facebook said the company’s software is ready to incorporate new persistent memories like XPoint for uses such as caches and database applications as soon as Intel and Micron can deliver products.

Facebook has been investigating various alternative memories including phase-change and memristor types. “After many years a new class of memories is on the horizon, but we are still in the early years exploring its applications,”Vijay Rao, a director of technology strategy at Facebook, told attendees in a keynote.

For its part, XPoint is “significantly faster than NAND,” he said, noting Intel published results showing its Xpoint SSDs delivering performance increases on Facebook database structures.

__Figure 2:__ *Micron showed 900,000 IOPS for its four-lane Quantx SSDs. (Image source: Micron)*

Toshiba drives flash forward

In a separate keynote, Toshiba disclosed plans to push conventional NAND to higher density and performance levels. It plans to deliver in 2017 a 512 Gbit NAND chip using 16 die linked via through-silicon vias to enable packages with a terabyte of storage. A follow on for 2019 could use 32 die to put 2 TBytes in a package.

The new chips will enable 64-100 Tbyte drives in the 2018-2020 time frame. Such SSDs aim to hit costs of 5-7 cents/Gbyte so they could start to replace mainstream hard-disk arrays used by large data centres today.

__Figure 3:__ *Toshiba’s road map calls for 32-layer TSV NAND chips that pack 2 TBytes in a package before 2020. (Image source: Toshiba)*

Separately, Toshiba now has working chips for QLC, a version of flash supporting four bits/cell. The dense designs could enable 100 TByte SSDs and beyond, initially using a PCIe Gen 3 interface.

One such drive could replace a dozen hard drives while offering significantly lower power consumption and higher performance. Toshiba plans to shift the designs to PCIe Gen 4 in 2019.

“We have started a conversation with hyperscale data centers who are in early level investigations and QLC works fine with their use cases,” said Shigeo Ohshima a technology executive in Toshiba’s SSD group.
Indeed, three years ago Facebook called for a high capacity, low cost write-once storage for what it called immutable data – perhaps a picture stored indefinitely on Facebook. Rao said 100 TByte QLC SSDs could serve that need that currently falls between flash and hard-drive costs.

“We are rooting for [vendors] to have this in production soon — now we want five levels per cell,” Rao quipped.

Separately, Toshiba announced its own storage system. The Flashmatrix packs CPUs, FPGA accelerators and a flash array into a 2U box. Fourteen of the systems can be linked into a 336 TByte array.

The Flashmatrix targets large data centers that lack the scale of a Google or Facebook that currently design their own storage arrays.

__Figure 4:__ *According to Toshiba, QLC drives can be used to replace mainstream hard disk arrays. (Image source: Toshiba)*

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