New Toshiba SSDs support 64-layer BiCS 3D NAND flash

Toshiba ships new client NVMe-based PCIe SSDs that support its latest 64-layer BiCS 3D NAND flash to improve performance and density and open the door to future price drops.

Toshiba launched a new line of client solid-state drives that support the latest 3D NAND flash and nonvolatile memory express technologies and could see limited use in enterprise systems.

The XG5 SSD is the first to use Toshiba's 64-layer Bit Cost Scalable (BiCS) 3D flash, offering the potential for higher densities and lower costs, when the ongoing NAND shortage subsides in the future. The NAND flash shortage has slowed price declines for Toshiba SSDs and all other SSD manufacturers, as chipmakers have struggled with the transition from 2D NAND to 3D NAND in the face of rising demand.

Grant Van Patten, Toshiba's product line manager of client PC, data center and embedded devices, said the company expects the flash cost curve to resume its previous downward trajectory once the shortage eases. He said Toshiba plans to transition the vast majority of its solid-state drives (SSDs) to 3D NAND flash, but the qualification time takes longer for enterprise SSDs than for consumer SSDs.

Brian Kumagai, director of business development for Toshiba's memory business unit, said the tight NAND supply would likely stretch through the end of the year and possibly into early 2018. Toshiba has yet to reach optimal yields of 90% to 95% per wafer with the BiCS 3D NAND technology that it achieves with its 15-nanometer 2D NAND, Kumagai said.

"The race is on in terms of 3D now. Trying to compete with 2D is not an option," said David Floyer, Wikibon co-founder and CTO. "Samsung had the market to themselves for a time, and they don't anymore. Micron and Toshiba both have, or will have, the same type of technology."

Greg Wong, founder and principal analyst at Forward Insights, said higher yields correspond to lower manufacturing costs -- savings that "will hopefully be passed on to end users."

Toshiba TLC flash enables higher capabilities

The new Toshiba SSDs use triple-level cell (TLC) NAND flash to enable higher capabilities, and they support four-lane PCI Express (PCIe) Generation 3 and the 1.2.1 revision of the NVM Express (NVMe) specification to boost performance and lower latency. The SSDs offer capacity options of 256 GB, 512 GB and 1 TB in a single-sided 22 mm-by-80 mm M.2 form factor.

The race is on in terms of 3D now. Trying to compete with 2D is not an option.
David Floyerco-founder and CTO, Wikibon

Floyer said naysayers used to say TLC NAND would never be reliable enough for enterprise use. But he said Toshiba's initial shipment of 64-layer TLC 3D NAND SSDs, stated commitment to higher density TLC 3D NAND for enterprise and consumer SSDs, and aggressive investment in new 3D NAND fabs show the technology is the way of the future for storage. Floyer said new server-based storage architectures could create the opportunity for new and different SSD form factors beyond the traditional 2.5-inch SSDs that are most common in the enterprise today because of their historic use with hard drives.

Van Patten said Toshiba would offer multiple enterprise form factors, including SAS and PCIe add-in cards, U.2 and M.2. He said the company would likely offer enterprise-class M.2 SSDs in a larger 22 mm-by-110 mm form factor.

The single-port XG5's primary target are laptops, notebooks and desktop portable computers, but Van Patten said Toshiba expects the XG5 SSDs to see enterprise use for booting servers, caching, logging and other supporting functions.

Van Patten said the XG5 NVMe-based PCIe Toshiba SSDs could also be used in all-flash or hybrid storage arrays that build in system-wide redundancy, enabling vendors to use client drives to reduce costs. He said, in addition to higher performance and lower latency, potential NVMe advantages include reduced power consumption and the ability to share memory.

But Van Patten acknowledged that, for mission-critical primary storage, traditional OEM customers favor dual-port, enterprise-class Toshiba SSDs that are rigorously tested and hot-swappable. Enterprise drives usually feature a low uncorrectable bit error rate and mean time to failure of 2 million to 2.5 million hours, as opposed to the 1.5 million hours with client SSDs such as the XG5 Series.

Toshiba XG5 NVMe SSD
The new Toshiba XG5 NVMe SSD based on 3D NAND.

NVMe segments should address 'different portions of the market'

Van Patten said Toshiba also ships the value-focused, low-powered BG SSD Series that enterprises use primarily for server booting. The company began shipping the NVMe-based, two-lane PCIe BG2 Series with 48-layer BiCS technology last year, and the 22 mm-by-30 mm M.2 Toshiba SSDs are now available in products, he said.

"We think there need to be different segments of NVMe that address different portions of the market," Van Patten said. "There needs to be an NVMe product that's cost-optimized specifically to compete with SATA in terms of pricing. That's really where we see the value NVMe category having the largest impact over the next couple years on the client side."

Toshiba said the XG5 SSDs are faster than SATA SSDs and produced a maximum sequential read performance of 3,000 MB per second (MBps) and sequential write performance of 2,100 MBps, although speeds can vary based on the host device, applications and file size.

The XG5 SSD includes a single-level-cell flash cache designed to speed workloads with burst potential. The product roadmap includes self-encrypting drive models, which will expand the use cases to include business applications requiring security.

Toshiba began shipping the XG5 in May to PC OEMs and expects to gradually expand availability to additional OEMs for enterprise and embedded systems in the second half of the year. Plans also call for a retail version based on the same XG5 hardware for the PC enthusiast and gaming space.

The release of the XG5 SSD line takes place as Toshiba reportedly pursues the sale of its memory business to cover losses from its struggling U.S.-based Westinghouse Electric nuclear power subsidiary.

"The financial troubles within Toshiba do not stem from the memory business, so from our perspective, it's business as usual," Van Patten said.

Toshiba's semiconductor joint-venture partner, Western Digital, has claimed no transaction can take place without its consent. Several of WD's SanDisk subsidiaries file a request for arbitration with the ICC International Court of Arbitration, operated by the Paris-based International Chamber of Commerce, related to three flash-memory joint ventures with Toshiba.

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