Emerging storage-class memory promises to fill the performance and density gap that currently exists between DRAM and SSD solutions.
Data creation is skyrocketing, propelled by trends such as edge computing, 5G networks, image processing, real-time voice processing, and an array of other sophisticated data generation and collection technologies. There’s also an increasing need for “big data” to perform real-time analytics on the fly. These trends are now combining to create the need for fast and affordable storage technology.
Unfortunately, current storage technologies, primarily DRAM and SSD, are failing to meet the performance and/or cost requirements necessary to ensure that data storage can keep pace with the demands presented by a wide array of disruptive technologies. Emerging storage-class memory (SCM) technology promises to solve the current storage challenge and support innovative data-driven technologies by filling the performance and density gap that currently exists between DRAM and SSD solutions.
While SCM is not a complete DRAM replacement, much of the data stored in DRAM could be stored in SCM instead. Equally important is the fact that SCM is denser and cheaper than DRAM. Additionally, with SCM, the swapping of data and instructions between DRAM and SSD can be significantly reduced, and the need to “boot” from an SSD can potentially be reduced or eliminated in the future. SCM fits well into the memory hierarchy because it’s a highly cost-effective approach to solving the current storage bottleneck — the volume of data transfer and the latency gap between DRAM and flash SSD.
DRAM’s Scale and Cost Issue
Although conventional DRAM has been available for a very long time, it’s beginning to show its age — and shortcomings. A major hang-up is the fact that DRAM is currently very challenging and costly to scale. Existing solutions can’t even approach NAND flash scale, especially in today’s era of 3D NAND flash. No matter how one views the situation, it’s apparent that the ability to scale DRAM die density is currently limited, expensive, and not likely to improve much over the near-term.
Filling the Gap
At present, the most promising approach to addressing DRAM’s drawbacks is turning to SCM. When combined with low-latency flash, SCM makes it possible to break down data transfer bottlenecks, effectively reducing the current latency gap. In the same way SSD and All Flash Array (AFA) technologies bridged the performance gap between HDD and DRAM, becoming a tier in the memory hierarchy, SCM is ready to emerge as the tier between SSD and DRAM.
SCM effectively bridges the density and latency gaps that currently exist between DRAM and flash storage at an affordable price. When combined with DRAM in front of the TLC or QLC storage, SCM can achieve performance on par with a DRAM-only solution.
Over the past several years, data has emerged as one of the world’s most valuable assets, serving the needs of businesses, government agencies, and consumers in an almost endless number of ways. Ensuring that today’s ever-rising data tide can be corralled quickly and cost effectively requires a powerful, cost-competitive memory solution. SCM is an approach well suited to meet this need.
The facts are plain to see. DRAM is at least two times more expensive per bit than the highest cost version of SCM. Kioxia’s XL-Flash SCM, for example, is also easily cost scalable with the company’s proven BiCS Flash technology, and is even more competitive with MLC-based XL-Flash. Total density available, meanwhile, is approximately two-times greater than DRAM. Looking down the road, MLC technology promises to further increase XL-Flash density compared to DRAM. Latency, meanwhile, is approximately 10-times improved over TLC Flash.
XL-Flash SCM also effectively addresses the compatibility issue. Using industry standard packaging, XL-Flash SCM is fully compatible with the current NAND interface, allowing easier adoption using existing SSD controllers.
Today’s data generation torrent shows no sign of slowing down. In fact, the rate of data creation is likely to continue accelerating at a virtually exponential rate for the foreseeable future. Fortunately, SCM — serving as the tier between SSD and DRAM — is available now to address the needs of a data-hungry world.
This article was originally published on EE Times.
Scott Nelson is senior vice president and general manager, Memory Business Unit, Kioxia America, Inc.