3D NAND is all the rage in solid-state drive (SSD) storage, whether in consumer, enterprise or industrial-embedded designs — perhaps especially in embedded designs.
NAND’s potential to dramatically boost flash-storage capacities well above those of planar (2D) NAND is well documented. Major flash makers have boasted of developing 3D NAND devices exceeding ever-increasing capacities on a single device, enabling once unfathomable storage in designs ranging from handheld devices to data centers. Less discussed, however, is how super-capacity 3D NAND flash storage can be deployed in demanding embedded systems, including industrial IoT (IIoT) and machine-to-machine (M2M) designs. Such applications take advantage of flash storage in different ways.
A quick review of 3D NAND: Planar NAND has been around since the beginning of flash memory. NAND cells are strung horizontally across a flat 2D plane. As capacity grows, the cells have shrunk to the point where no more will fit without data loss. To overcome that limitation, 3D NAND is created when planar NAND is reformed into a U shape, flipped into a vertical orientation and “stacked” like a high-rise building, thus dramatically increasing storage capacities within essentially the same footprint as 2D flash needs.
Since its inception, 3D NAND has gained serious traction, with all major flash memory makers having added it to their flash products. Flash-storage market researcher and author Alan Niebel said, “Thanks to its scalability and cost-per-bit advantage, 3D NAND flash is poised to revolutionize both enterprise and industrial solid-state storage.” In terms of the volume shipments of NAND, both planar and 3D, another market analyst predicts that in 2021 six times as many flash exabytes will ship as did in 2016.
Also contributing to flash’s ever-increasing capacities is that the mainstream bit capacity is now three bits per cell, or Triple Level Cell (TLC) technology with Quad Level Cell (QLC) at four bits per cell in the future.
With all these new 3D approaches to manufacturing, there are tradeoffs – and we should expect some sort of compromise between endurance, performance, thermal considerations and capacity. After all, packing three – and eventually four — bits per cell into the chips and then manufacturing them into a layered solution is a relatively new concept that’s still in the improvement stage, and therefore subject to initial endurance, performance and thermal challenges.
NAND flash designers are overcoming the endurance and thermal barriers, but it has come at a price. Industrial-temperature 3D-based solutions have not reached the industrial-embedded market until recently, several years after mainstream commercial and enterprise versions have been on their respective markets. It has taken some time to adapt this technology to the industrial market, but it appears the engineers working with 3D NAND are learning how to do just that. 3D-based SSDs will not have to sacrifice endurance and are now matching and exceeding the endurance of 2D MLC-based SSDs.
Industrial-temperature rated 3D NAND flash is here. But the thermal effects on 3D SSD performance are still fairly new subject matters and need further validation testing of workload and extreme temperature ranges. 3D NAND is in mainstream markets, but high-temperature use of 3D NAND is still in its infancy.
While 3D NAND SSDs have been proven for consumer applications and possibly select enterprise storage environments, the industrial-embedded market simply can’t compromise data integrity for the sake of capacity. Industrial 3D SSD applications such as factories, medical equipment and smart cities, to name just a few cannot afford a breakdown in their data-storage systems; lives and livelihoods depend on them and that data is mission-critical. Industrial users have time-and-again affirmed this: SSD durability and data protection are non-negotiable — even in the most extreme environments. This highlights the distinctions between off-the-shelf SSDs and those designed and built for such mission-critical applications.
Because IIoT endpoints are usually found in harsh and/or remote environments, the SSDs used here must be able to support extreme temperatures – I-Temp (-40°C to 85°C) is the industry standard for temperature tolerance — along with vibration and shock that can be offset by special SSD manufacturing processes. They also must be built for a “set it and forget it” purpose and be subject to monitoring and predictive analysis through software.
One more matter to consider in industrial 3D NAND storage is protecting the data embedded systems collect. Like its 2D predecessor, 3D NAND-based SSDs can realize data security through encryption. Self-encrypting SSDs using the Advanced Encryption Standard (AES) — regarded as the de facto security standard for the U.S. government — provide a solid assurance that data at rest is protected.
Again, the SSDs’ applications and the critical data they collect and store simply cannot fail.
Clearly, there’s far more at stake in embedded-system, IIoT and M2M data collection and storage applications. And those stakes serve as guiding factors as flash makers develop storage with significantly higher capacity, as we’re witnessing in 3D NAND.
Evolving 3D NAND development, coupled with proven industrial-grade production techniques and encryption techniques SSD providers such as Virtium use, will support the demanding storage needs of the industrial-embedded market.
Whatever the “growing pains” of 3D NAND, embedded-system engineers can be assured that SSDs built around this new dimension of storage will provide the drive durability and data protection required.
Scott Lawrence is Director of Business and Technology Development, Virtium Solid State Storage and Memory.