Samsung at Flash Memory Summit: 64-layer V-NAND, Bigger SSDs, Z-SSD

At Flash Memory Summit, Samsung announced their fourth generation of 3D NAND and several of the more obvious SSD upgrades it enables. Taking a page from Intel and Micron’s strategy book, they also announced a new memory type and corresponding SSD product while saying essentially nothing about what the new memory actually is.

Gallery: Samsung 4th Generation V-NAND

The fourth generation 3D NAND bumps the layer count up to 64, compared to the 48-layer design used by the third generation V-NAND that was announced last fall and has been slowly rolling out to their SSD products over the course of this year. So far Samsung has talked about a 512Gb TLC part, and at least initially the MLC parts will probably be made from the same die and thus have two thirds the capacity. (Samsung’s second generation 3D NAND was initially available as 128Gb TLC or 86Gb MLC, with 128Gb MLC parts introduced later.) The new NAND also supports an increased interface speed of 800Mbps, which is key to reducing the performance penalty that comes from consolidating more flash onto fewer independent chips.

With a per-die capacity of 512Gb (64GB), Samsung can now put 1TB of TLC flash in a single package. This means most product lines will be seeing an increase in capacity at the high end of the range. Their BGA SSD products will be offering 1TB capacity even in the 11.5mm by 13mm form factor. The 16TB PM1633a SAS SSD will be eclipsed by the new 32TB PM1643. Likely to be further out, the PM1725 PCIe add-in card SSD will be succeeded by the PM1735 with a PCIe 4 x8 host interface.

Complementing the NAND update will be a new non-standard oversized M.2 form factor 32mm wide and 114mm long, compared to the typical enterprise M.2 size of 22mm by 110mm. A little extra room can go a long way, and Samsung will be using it to produce 8TB drives. These will be enterprise SSDs and Samsung showed a diagram of these enabling 256TB of flash in a 1U server. Samsung will also be producing 4TB drives in standard M.2 sizing.

Gallery: Samsung Z-NAND and Z-SSD

In what is likely a bid to steal some thunder from 3D XPoint memory before it can ship, Samsung announced Z-NAND memory technology and a Z-SSD product based around Z-NAND and a new SSD controller. They said nothing about the operating principles of Z-NAND, but they did talk about their plans for the Z-SSD products.

Samsung Z-SSD is being marketed as addressing the performance gap between DRAM and SSDs. Samsung’s slides during their keynote showed some performance comparisons against the PM963 NVMe TLC SSD and against an unnamed “PRAM based” solution. The logical point of comparison would be against 3D XPoint NVMe drives, but Samsung can’t have real performance and power numbers on those when they’re still under development by Intel and Micron. Thus the PRAM based solution Samsung refers to is probably one of their own earlier R&D efforts that didn’t make it to market. The Z-SSD ties or comes out ahead on every benchmark Samsung showed, but NVMe NAND flash SSDs were missing from the power consumption comparison.

The slides stated that there will be a 1TB Z-SSD this year and 2TB and 4TB Z-SSDs next year, while the press release issued later states that more generally that the Z-SSD is expected to be released next year. The press release also states that Z-NAND “shares the fundamental structure of V-NAND and has a unique circuit design and controller that can maximize performance”. Given that, the launch timeframe and capacities that are only a little lower than NAND flash SSDs, it seems that Z-NAND isn’t drastically different from existing memory technologies and it may even be little more than SLC flash in disguise, trying for a comeback.

Micron Announces QuantX Branding For 3D XPoint Memory (UPDATED)

In a keynote speech later this morning at Flash Memory Summit, Micron will be unveiling the branding and logo that their products based on 3D XPoint memory will be using. The new QuantX brand is Micron’s counterpart to Intel’s Optane brand and will be used for the NVMe storage products that we will hear more about later this year. 3D Xpoint memory was jointly announced by Intel and Micron shortly before last year’s Flash Memory Summit and we analyzed the details that were available at the time. Since then there has been very little new official information but much speculation. We do know that the initial products will be NVMe SSDs rather than NVDIMMs or other memory bus attached devices.

In the meantime, Micron VP Darren Thomas goes on stage at 11:30 AM PT, and we’ll update with any further information.

Gallery: Gallery Title

UPDATE:

Micron’s keynote reiterated their strategy of positioning 3D XPoint and thus QuantX products in between NAND flash and DRAM, with the advantages of 3d XPoint relative to each highlighted (while the disadvantages go unmentioned). But then they moved on to showing some meaningful performance graphs from actual benchmarks of QuantX drives.

The factor of ten improvement in both read and write latency for NVMe drives is great, but perhaps the more impressive results are the graphs showing queue depth scaling. In a comparison of U.2 NVMe drives, Micron showed performance of QuantX drives ranging from 200GB to 1600GB, relative to a 1600GB NAND flash NVMe SSD. The QuantX drives saturated the PCIe x4 link with a 70/30 mix of random reads and random writes with queue depths of just 4-6, while the NAND SSD gets nowhere close to saturating the link with random accesses. The next comparison was of the PCIe x8 add-in card performance, where the link was saturated with queue depths between 10 and 16, depending on the capacity of the QuantX drive.

This great performance at low queue depths will make it relatively easy for a wide variety of workloads to benefit from the raw performance 3D XPoint memory offers. By contrast, the biggest and fastest PCIe SSDs based on NAND flash often require careful planning on the software side to achieve full utilization.

Seagate Introduces 10GB/s PCIe SSD And 60TB SAS SSD

Seagate is looking to break records with two enterprise SSDs they’re showing off at Flash Memory Summit this week. The first drive is one that’s been seen before: the 10GB/s PCIe x16 SSD that Seagate demonstrated in March. It has now been named the Nytro XP7200 and is scheduled for mass production in Q4. Based on four Nytro XM1440 M.2 SSDs under one heatsink on a full height expansion card, the XP7200 is more of a backplane than a drive on its own. Unlike some other multi-controller PCIe SSDs, the XP7200 does not include a PCIe switch chip. This means that the card can only be fully utilized in PCIe x16 slots that support operation as four separate x4 links. Plugging the XP7200 into a PCIe x8 slot would render two of the four M.2 drives inaccessible. And because there are four independent NVMe SSDs on the card, hitting the peak advertised read speed of 10GB/s requires the use of software-based RAID-0 or a similar striping scheme.

The performance specifications of the XP7200 show clearly the impact of using the capacity-optimized XM1440 models rather than the endurance optimized versions. Despite boasting total sequential read speeds of 10GB/s and almost one million IOPS for 4kB random reads, the write performance isn’t earth-shattering. The XP7200 will be available in capacities of either 3.8TB or 7.7TB, as a result of populating it with either the 960GB XM1440 or the newer 2TB model.

With the Nytro XP7200 moving toward production, Seagate has brought out another SSD tech demo with eye-catching specifications. The unnamed SAS SSD packs 60TB of 3D TLC into a 3.5″ drive. In order to connect over a thousand dies of Micron’s 3D TLC NAND to a single SSD controller, Seagate has introduced ONFi bridge chips to multiplex the controller’s NAND channels across far more dies than would otherwise be possible. The rest of the specs for the 60TB SSD look fairly mundane and make for a drive that’s better suited to read-intensive workloads, but the capacity puts even the latest hard drives to shame.

The 60TB SSD is currently just a technology demonstration, and won’t be appearing as a product until next year. When it does, it will probably have a very tiny market, but for now it will give Seagate some bragging rights.