Is NVM Express (NVMe) overkill for embedded, industrial applications?
Until recently, that's been the consensus, according to Scott Phillips, vice president of marketing at Virtium. But as big players such as Intel and Micron push the interface specification forward, Phillips said many industrial customers are approaching the company and asking about NVMe. In a telephone interview with EE Times, he said they see the potential benefits of the Internet of Things (IoT) and sensors that generate large volumes of data about operations, but don't know how to get started.
Phillips said that as Virtium's business model is one of “first in, last out," it's supporting DRAM that's been around for as long as eight years, while also having to be forward thinking about new technologies such as the demands of IoT and the role of NVMe. Right now, customers looking at it don't need the performance it offers, but as it goes mainstream it will end up having a place in embedded industrial applications.
He said most of the focus around NVMe SSDs to date has been in the data center with a focus on performance and how many millions of IOPs were possible. “They're not worrying about power, just cranking out data," Phillips said.
Power and heat must be taken into account for the fan-less designs required in the industrial embedded segment, and Phillips said the current approach of throttling drives make sense in the data center, but industrial OEMs don't want to see those kinds of ups and downs. “They want to see a steady state," he said.
This is starting to change, however, as controllers become small enough for the M.2 form factor, and power consumption is reduced in NVMe drives. Phillips said the ideal target is below 4 watts; it's still around 5 watts and can be throttled using firmware. Throttling higher wattages to bring them down is too dramatic a drop.
Aside from the current NVMe conundrum, there is also the ramp up of 3D NAND, which is getting a lot of attention. But for most customers in the industrial embedded space, planar meets their needs, with 2D 15nm NAND having been available for more than a year. They're looking for something that can be left in a piece of equipment without having to touch it again for years to come, said Phillips, while SATA remains “bullet proof" for their needs as well.
Phillips said the tipping point for embedded NVMe will be latency when applications need the less than 3ms it offers. But right now, that's few and far between, he added.
One potential niche application is inflight entertainment systems offering movies, games and Wi-Fi access. “There's a lot more going on now," Phillips said. "They're hitting those little servers in the planes a lot quicker and with a lot more different requests, so they're now concerned about lowering latency for response times."
The NVMe protocol does have the features to support embedded and IoT requirements, said Jonmichael Hands, NVM Express Inc.'s marketing committee co-chair. Ultimately, meeting the needs for industrial customers comes down to the designers of the products. Hands said the latest specification update does include features that makes it well-positioned for embedded and IoT use cases. For example, NVMe 1.3 supports bootstrapping in low-resource environments, including mobile, which will allow for lower cost NVMe devices in smaller spaces, such as the M.2 form factor.
The specification also recognizes that 3D NAND might be have more density than many embedded applications require, and supports other NVM options, said Hands. There are also a lot of thermal and power requirements in embedded, he said, but there a “boatload" of power features in NVMe such as autonomous power state transition, thermal management and near-zero power idle states. “It's really up to implementers and vendors to decide if they want to make something specific to that embedded segment," he said.
Hands said as IoT grows into edge analytics and autonomous driving, there will be a need for faster bandwidth and lower latencies. “That's going to be a clear transition where they're going to be requiring NVM Express," he said. “It's better to invest in a single technology in the longer term for controllers and architectures, so embedded is adopting similar designs to the client and data center."
And while SATA does have an established track record, Hands doesn't equate that with being more stable than NVMe, as the latter has been shipping since 2014. “It's just a legacy interface," he said. “People are getting serious about developing purpose-built NVMe devices for these markets."
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