Given that we are anticipating a launch of the Samsung 850 EVO very shortly, it is a good time to back fill on the complete performance picture of the 850 Pro series. We have done several full capacity roundups of various SSD models over the past months, and the common theme with all of them is that as the die count is reduced in lower capacity models, so is the parallelism that can be achieved. This effect varies based on what type of flash memory die is used, but the end result is mostly an apparent reduction in write performance. Fueling this issue is the increase in flash memory die capacity over time.
There are two different ways to counteract the effects of write speed reductions caused by larger capacity / fewer dies:
- Reduce die capacity.
- Increase write performance per die.
Recently there has been a trend towards *lower* capacity dies. Micron makes their 16nm flash in both 128Gbit and 64Gbit. Shifting back towards the 64Gbit dies in lower capacity SSD models helps them keep the die count up, increasing overall parallelism, and therefore keeping write speeds and random IO performance relatively high.
Introduction, Specifications and Packaging
It seems a lot of folks have been incorporating Silicon Motion's SM2246EN controller into their product lines. We first reviewed the Angelbird SSD wrk, but only in a 512GB capacity. We then reviewed a pair of Corsair Force LX's (256GB and 512GB). ADATA has joined the club with their new Premier SP610 product line, and today we are going to take a look at all available capacities of this new model:
It's fortunate that ADATA was able to sample us a full capacity spread, as this will let us evaluate all shipping SSD capacites that exist for the Silicon Motion SM2246EN controller.
Introduction, Specifications and Packaging
A few months back, we took a look at the ADATA Premier Pro SP920 series of SSDs. Those came equipped with the Marvell 88SS9189 controller. Marvell SSD controllers have always done a good job, and they were among the first to support SATA 6Gbit speeds. Crucial was one of the first to adopt the Marvell controller into their SATA SSD products, so it seems fitting that we revisit the 88SS9189 controller in the form of Micron's Crucial M550 Series of SSDs:
Being one of the big manufacturers of SSDs, Micron has some cool production videos. Here's one of their videos covering the production of flash all the way through to the assembly of an SSD. We actually toured one of these plants a few years back. Good stuff:
Subject: Storage | August 14, 2013 - 10:11 AM | Tim Verry
Tagged: Samsung, charge trap flash, vertical nand, vnand, 128Gb, enterprise ssd
Last week, Samsung announced that it had started producing a new stackable NAND flash memory called V-NAND, or vertical NAND. The new 3D V-NAND would initially be available in 128Gb (Gigabit) chips, but could eventually scale into as much as 1 Tb (Terabit) per chip by stacking additional dies vertically. Doing so allows Samsung some flexibility in scaling to higher capacities without going to increasingly expensive and difficult to manufacturer smaller manufacturing processes, which has been the traditional method of attaining denser flash.
The company has now announced the V-NAND SSD, which is its first Solid State Drive to use the Vertical NAND technology. Aimed at the enterprise server market, the V-NAND SSD will come in 480GB and 960GB capacities. The 2.5” form factor drives are 7mm thick and come equipped with a SATA III 6Gbps controller. On the high end, the 960GB model uses 64 MLC 3D V-NAND 128Gb dies for a total physical capacity of 1TB. However, user-accessible capacity will be only 960GB. Unfortunately, Samsung did not reveal how many physical chips the drives use, so its hard to say how those 64 128Gb dies are distributed (4 high in 16 chips or 8 high in 8 chips, etc).
The 960GB Samsung V-NAND SSD spotted by Engadget.
Samsung claims that the V-NAND SSD offers up to 20% increased performance and a 40% reduction in power consumption versus previous SSDs. Further, the 3D NAND using Samsung’s Charge Trap Flash technology is rated at 35K program erase cycles. Samsung rates the V-NAND memory itself as being twice as fast in writes and between two and ten times as reliable versus traditional 19nm floating gate NAND (the alternative to CTF NAND).
Samsung's 128Gb V-NAND die.
Samsung stated in a press release that it started production of the V-NAND SSD earlier this month. While it is introducing V-NAND into enterprise drives first, the technology will eventually trickle down into consumer drives. I’m interested to see this drive benchmarked for performance and write endurance to see if the 3D flash lives up to its potential.
Subject: General Tech | August 6, 2013 - 01:56 AM | Tim Verry
Tagged: Samsung, vnand, vertical nand, charge trap flash, 128Gb, nand
Today, Samsung announced that it has begun mass production of a new kind of 3D NAND flash memory that offers up higher reliability and write performance versus traditional 2d “planar” technologies. The so-called VNAND (Vertical NAND) is currently being used in 128Gb (Gigabit) flash chips (matching current 2D flash chips), but the technology has the potential to go much further in terms of capacity.
The VNAND combines an updated version of Samsung’s Charge Trap Flash (CTF) technology (originally developed in 2006) with a vertical stacking and interconnect technology that uses special etching techniques to punch holes and electrical connections down from the top of the highest die to the bottom die.
Samsung claims that its proprietary interconnect technology is (currently) able to support up to 24 layers of flash memory. The resulting VNAND offers up to twice the write performance and between 2-times and 10-times higher reliability versus traditional 19nm floating gate NAND (the alternative to CTF NAND) developed on planar processes.
With traditional NAND flash, as flash density increases (such as the move from 25nm to 19nm NAND flash), inter-cell interference also increases due to thinner walls and increased leakage. Samsung is hoping to solve that problem with its vertically-stacked NAND by allowing density to increase without dealing with shrinking the individual layers. Further, each layer is separated by a dielectric (electric insulator) that is currently 50nm and constructed of Silicon Nitride (SiN). The company notes that there is a limit to the height at which flash can be stacked before it becomes un-economical, but that is still a ways off compared to where NAND flash is now as far as densities seen in the wild.
Samsung’s new 128Gb VNAND chip is expected to scale to at least 1Tb depending on consumer demand. The technology is aimed at both embedded NAND and SSDs, but the former is likely to make use of 3D vertical NAND first. Standard 2.5" SSDs could also benefit but modern SSDs are already bottle-necked by the SATA III 6Gbps bus much less by faster write speed potential. Mobile devices, however, could benefit from faster single-chip VNAND packages immediately with faster write speeds and higher reliability (and potentially, density) versus 2D NAND chips.
It is definitely a technology with potential that is worth keeping an eye on.
The full press release can be found over at Engadget.