Earlier this year, Samsung started talking about a new NAND storage technology it planned to bring to market. The company has been close-mouthed about its new Z-NAND and the Z-SSD it powers, though it did share the technology is based on its three-dimensional V-NAND, otherwise known as 3D NAND. Early performance data on Z-NAND and its first PCI Express SSD has begun to surface and Samsung is clearly gunning for Intel’s Optane with this product.
Samsung has been extremely coy on what NAND technology is baked into Z-NAND or what consumers should expect, but let’s break down what we’ve got. The company has repeatedly said Z-NAND features an improved NAND controller, but most manufacturers keep the secrets of their NAND controllers tightly under wraps and don’t share them with the press. We do know, however, Z-NAND “shares the fundamental structure of Samsung’s V-NAND.” “Fundamental structure” is a vague phrase, but we can safely assume Z-NAND is a three-dimensional NAND with an unknown number of stacks. We know standard V-NAND is built on 40nm, and it seems likely Samsung is still using that node for Z-NAND as well.
Samsung could have gone back to an earlier process node than 40nm to scale up its enterprise Optane competitor, but this seems unlikely. While older nodes tend to offer higher reliability and faster performance than smaller ones, but Samsung already tapped 40nm for this reason and falling back to an earlier node for a limited run product makes little sense. Right now, the smart money seems to be on a tweaked controller architecture and the use of SLC NAND (single-level cell). The more data you store per bit of NAND flash, the slower the access time and the lower the NAND’s endurance.
Image via PC Perspective
A graph released last year indicated Samsung expects to bring costs down between the first and second generations of Z-NAND, but without graph labels we don’t know how big of an improvement these data points represents.
Samsung is claiming numbers that nearly match Optane, along with an equal number of drive writes per day (30 total, identical to Intel’s P4800X). The company has also published a variety of its own benchmarks, showing its new drive delivers dramatically better performance than its previous efforts in this space. We’ve rounded up some of these for the slide show below. All data is from Samsung, as are the test descriptions.
RocksDB is a popular “key value” store that serves as a back end to other applications and databases (e.g. MongoDB, Redis, MySQL, etc.) and is prevalent in many data center productions stacks. Our RocksDB performance benchmarking illustrates a large increase in throughput as a result of the decrease in Z-SSD device latency.
Overall, Samsung’s data set shows credible performance improvements for Z-NAND, and a potentially potent challenger to Intel’s Optane. The bigger question, however, is which company will be able to sustain improvements year-on-year. The NAND flash ecosystem is mature at this point and while advances in throughput and performance could absolutely still happen, the last few years have been as much about driving NAND costs lower as about boosting performance. Intel is at the hypothetical beginning of 3D XPoint’s ramp, and should have much more runway to boost its performance over what’s available today.