Tom's Hardware: Best Of Flash Memory Summit 2015

Flash Memory Summit 2015 is over, but the technology legacy will carry on for years to come. This year we saw an increased presence in enterprise products with a large focus on large scale All Flash Array (AFA) systems. I've been going to the show for five years now and am saddened to report that client flash products have all but disappeared. A few companies like Phison, Silicon Motion and Toshiba displayed next generation NVMe products designed for the client space, but many of the long hold outs like Adata, which presented last year, didn't participate in 2015.

Awards And Award Criteria

Tom's Hardware, in association with Tom's IT Pro, our sister site that focuses on IT and datacenter content, chose to give awards to standout products, features or upcoming technology announced at Flash Memory Summit 2015. Over the last several months, several new technologies have been announced, but we chose to only award new items announced at the show. Products like IMFT's 3D XPoint (Cross Point) that were previously announced were not eligible, nor were products not on display.

The team working behind the scenes at Flash Memory Summit have been good to us over the years, and we hope our contribution encourages companies to use the show as a launch vehicle more in the future. FMS is a wonderful event that focuses on non-volatile memory and surrounding technologies. We call the show the "Super Bowl of Flash."

Samsung 256 Gb 3-bit Per Cell NAND Flash

Samsung recently announced a transition to 48-layer 3D NAND flash for use in upcoming products. This increased the die density of MLC to 128 Gb, up from 86 Gb. Unbeknownst to us until FMS 2015 was the fact that Samsung's third-generation 3D cell structure would increase the die density of TLC from 128 Gb to 256 Gb.

Competitors in the NAND flash manufacturer market have already announced 256 Gb products, but IMFT, SK Hynix and Flash Forward publicly stated that new 3D structures with 256 Gb density will not ship in retail products until 2016. That's what makes Samsung's new 256 Gb TLC stand out from the crowd. Samsung will start mass production in the coming weeks and will have a product on retail shelves by the end of 2015.

In a keynote at the show, Samsung alluded to TLC replacing MLC in many client products. Other companies have stated as much. Companies are under pressure to reduce the price of SSDs for all areas of the computer market, from servers to tablets and all the way down to point of sale (POS) systems used in check out lanes.

Samsung's third-generation V-NAND uses dual planes, so smaller capacity SSDs will not lose performance like we saw in the transition from 64 Gb die to 128 Gb die. Even so, Samsung could also use the new die to increase capacity without significantly increasing retail prices.

Just one month ago, Samsung released the 850 Pro and 850 EVO products in 2 TB capacity sizes using 32-layer die with eight packages (review here). It appears the company still has a use for older V-NAND, but we can think of one market that will require higher density flash to satisfy user demands. PCIe SSDs in the client space are dominated by the M.2 form factor. These come in several configurations, with 22 mm width setting the standard. The length, however, can change depending on the space available. A standard that is 22 mm wide and only 40 mm long, the 2240, can only hold two NAND packages when paired with a controller and DRAM package to cache the table map. Dual planes will allow the drive to perform like a current-generation product with four packages using a single plane. This increases the performance of the product while reducing power consumption by as much as 30 percent.

On the other side of the coin, M.2 22110 with more space for additional NAND packages could scale density to higher levels. My estimate with high density packages is up to 4 TB or even 8 TB using Samsung's new 256 Gb V-NAND technology.

Toshiba TSV NAND Technology

Samsung wasn't the only company making flash announcements at FMS 2015. For the first time, we were able to see Toshiba's Through Silicon Via, or "TSV" for short. We've found documents on Toshiba's website that discuss TSV dating back to 2007, but a recent announcement moved the technology from paper to real silicon.

PMC Sierra really put TSV into focus for us with a working product on display at FMS 2015. There we saw Toshiba's TSV in action with very sensitive test equipment logging the power of two identical products, with the NAND flash being the only variable. The TSV SSD increased efficiency, using less power to complete the same workload. Small amounts of power reduction add up over time, a point we make in all of our consumer-class SSD reviews, where one product can extend notebook battery life by over an hour compared to another. In the datacenter, where thousands of SSDs are deployed, a modest power reduction equates to millions of dollars in savings over a very short period of time.

Toshiba's TSV technology that eliminates wire bonding at the edge of the NAND flash die also increases performance, as data traffic has a straight path through the die instead of around it. Moving from the edge to the center also increases data integrity.

The largest gains from using TSV technology surround the density of the flash package. Companies are already able to stack up to 16 die per package, but the technique is not ideal. If a mistake happens in the packaging process, then all of the die become unusable. Stacking that many die also adds resistance, as the top die need longer bonding wires. This forces companies to run the high speed Toggle flash at lower speeds to ensure data integrity.

Phison PS5007-E7 SSD Processor

We first discussed Phison's first NVMe controller back in June at Computex, but the controller wasn't announced or on public display. The company only allowed a few select media to travel to a secret location set up for customers and was reluctant about talking about the product. Flash Memory Summit 2015 was the official unveiling for the E7, and the controller is very close to completion.

Over the next 12, months every SSD controller maker will release NVMe protocol controllers that interact with host systems over the PCIe bus. Presently, two known products are shipping or are very close to shipping. Intel's SSD 750 based on an enterprise controller is already in the market, and Samsung should have SM951-NVMe M.2 drives shipping by the end of the month. Both competing products are exclusive to their respective manufacturer. If the roadmap holds, Phison will have the first client NVMe processor available to third-party SSD manufacturers that source controller technology from other companies.

Phison has a long history in the SSD market and has sold products to several companies known for pushing the performance and price envelope, such as Corsair, Kingston, Adata and others. The fabless companies are the ones responsible for pushing retail SSD prices down through fierce competition. The cost of developing a proprietary controller is enormous, so the companies rely on Phison and others to develop controllers that are then sold to a broad group of builders. This approach strengthens the technology, as the collective works to further improve the products with firmware and programming changes sent back up to Phison. The changes are made and then shared back to everyone via firmware changes.

The Phison PS5007-E7 appears to be the closest next-generation NVMe controller from a third-party maker. It's also one of the fastest we've tested behind closed doors, just slightly faster than Marvell's Eldora (which we tested at Computex). The performance numbers shown on the image above were confirmed in Iometer with full random data. Performance may increase with compressible data like previous Phison controllers.

Phison plans to use the E7 in both client and enterprise systems with provisions for the latter to use power capacitors to flush data in a host power fail event. Phison doesn't sell SSDs to the public, but full solutions to companies that then bring a retail product to market. At Computex we saw the E7 in several booths in both M.2 and 2.5" form factors. A Phison representative hinted to us that the platform is currently undergoing optimizations but is very far along in the process.

Chris Ramseyer is a Contributing Editor for Tom's Hardware, covering Storage. Follow him on Twitter and Facebook.

Chris Ramseyer
Chris Ramseyer is a Contributing Editor for Tom's Hardware US. He tests and reviews consumer storage.