Page 19 - EE|Times Europe Magazine - December 2020

EE|Times EUROPE — The Memory Market 19

SPECIAL REPORT: MEMORY TECHNOLOGY
NVMe-oF Is Ready to Go the Distance

By Gary Hilson

fter a slower-than-expected start, is NVMe over Fabrics nect Express (PCIe) bus to transfer data locally. NVMe-oF, introduced
(NVMe-oF) finally taking off? five years after the original, is 90% similar to its predecessor, accord-
As an extension of the somewhat-mature nonvolatile ing to the NVM Express organization, which oversees the protocols.
A memory express (NVMe) protocol, the NVMe-oF specifica- NVMe-oF found an early champion in Micron Technology. In 2017,
tion uses NVMe to connect hosts to storage across a network fabric. Micron opted to move ahead of the standard with its own SolidScale
NVMe-oF supports the transfer of data between a host computer and architecture, which was created for low-latency, high-performance
a solid-state storage device or system over a network. Using an NVMe access to compute and storage resources and specifically addressed
message-based command, these transfers can be done via Ether- CPU underutilization in the data center. NVMe SSDs deployed in
net, Fibre Channel (FC), or application servers at the time were, on average, using less than 50%
The ability to use InfiniBand. of their I/O operations/second (IOPS) and capacity.
The company has since opted to sunset SolidScale, concluding that
A key value proposition
NVMe-oF across a of the fabric is that it can it didn’t make sense to compete with some of its own customers,
standard Ethernet connect distributed pools according to Joe Steinmetz, storage system architect and fellow with
Micron. It will focus instead on its core strengths as an SSD and mem-
of storage (most likely an
network without having NVMe SSD, although other ory supplier within the NVMe-oF ecosystem. This might finally be the
technology’s time, Steinmetz said, and there’s sufficient alignment
persistent memory could
to make configuration potentially be used down the within the industry to make it so.
Barriers to adoption nonetheless remain. While the inclusion of
changes may be what road). Furthermore, with the TCP and a non-remote direct memory access (non-RDMA) trans-
ability to use Transmission
ultimately drives its Control Protocol (TCP), con- port was deemed beneficial, it created some confusion, according to
adoption. nection can be accomplished Steinmetz. “That is one reason why NVMe over Fabrics has been a
bit delayed from when I think a lot of the industry expected [it] to be
over a distance. The most
recent revision of the speci- there,” he said. Another significant barrier is the software ecosystem;
fication, NVMe-oF 1.1, includes support for the TCP transport binding, depending on how the customer plans to use NVMe-oF, that ecosys-
which makes it possible to use NVMe-oF across a standard Ethernet tem is still in its infancy, said Steinmetz.
network without having to make configuration changes or implement While TCP solved the distance challenge — and it helps that
special equipment. TCP is everywhere — it doesn’t negate the applicability of RDMA
This ability may be what ultimately drives NVMe-oF adoption while over Converged Ethernet (RoCE), with which many of the storage
extending the core value of NVMe — unlocking the full benefits of OEMs have a great deal of experience. “TCP is useful, needed, and
NAND flash. It’s something that couldn’t be done by architectures will eventually drive adoption, [but] I don’t see RoCE going away,”
originally built for hard-disk drives with protocols such as internet Steinmetz said.
Small Computer Systems Interface (iSCSI). For the immediate future, Steinmetz sees all-flash storage array ven-
The original NVMe specification was published nearly a decade ago. dors as the first movers with NVMe-oF because they want to unlock the
It takes advantage of a computer’s Peripheral Component Intercon- value of the expensive flash for customers to enable full access to the

The NVM Express roadmap has steadily expanded the original specification. NVMe-oF, with TCP transport binding support, provides the
ability to scale storage over distances. (Source: NVM Express)

www.eetimes.eu | DECEMBER 2020