Experts anticipate that NVMe SSD storage will become the predominant solid-state drive standard.
Unlike the Advance Host Controller Interface (AHCI) -- the hardware mechanism that SATA SSDs use for data flow -- the nonvolatile memory express (NVMe) protocol was designed from the ground up to govern solid-state memory. It's optimized for flash-based technology, which positions NVMe to replace AHCI SSDs.
NVMe SSD storage brings an extensive list of enhancements and optimizations to the data storage market, said Walter Hinton, senior director of product marketing for storage technology vendor Western Digital.
"This can dramatically raise the bar for the benefits that can be had from present and coming software," he said.
Fulfilling SSDs' potential
Businesses recognize the fact that, if they want to truly benefit from SSD performance, they must move toward greater adoption of NVMe SSD storage, which utilizes the Peripheral Component Interconnect Express (PCIe) interface, said Ian McClarty, president and CEO of IT services provider PhoenixNAP Global IT Services.
"This allows for direct attachment of storage to [the] PCI bus and gets you as close as possible to the CPU," he said.
With the introduction of SSDs, SATA interfaces became a limiting factor; bandwidth thresholds stuck at approximately 600 MBps.
"AHCI also fails to take advantage of SSD characteristics, where AHCI respects the limitations of spinning disks with spinning platters and head movements by limiting or holding off commands that it sends," said Luke Pruen, technical services director at StorMagic, a software-defined storage provider.
With the assistance of technologies such as PCIe and M.2 -- which have significantly more bandwidth than SATA or even SAS connections -- NVMe is a protocol designed to communicate with and understand SSD characteristics.
"NVMe plays to the strengths of flash storage, allowing for multiple data requests per request, less time to decode a request and does not require thread locking," Pruen said.
NVMe also opens the door to next-generation storage media.
"SCM [storage-class memory] is just beginning to enter the picture in enterprise storage and, some day, may completely replace SSDs," said Dan Cobb, a vice president and fellow at Dell EMC. For now, most organizations will use NVMe with SSDs, which improves latency but comes at a premium. SCM, such as Intel Optane, "could be the X-factor in the next generation of storage, with much lower latency than NAND flash," Cobb said.
Lower latency and more
For large enterprises running latency-sensitive business applications at scale, [NVMe SSD storage] means faster data and faster results, which can lead to competitive advantages.
Henry HeDirector of Product Management, Virtual Instruments
Lower latency is the immediate benefit offered by NVMe SSD storage.
"For large enterprises running latency-sensitive business applications at scale, [NVMe SSD storage] means faster data and faster results, which can lead to competitive advantages," said Henry He, director of product management at Virtual Instruments, an infrastructure performance management vendor. "From a set of tests conducted by the NVM Express organization, I/O latency was observed to be in the range of 64% to 51% of comparable SAS/SATA drives under the same workload and same host system."
Beyond improved latency, NVMe SSD storage utilizes PCIe's speed and multi-lane advantages to accelerate storage processes.
"All else being equal, you get a boost in your storage performance KPIs [key performance indicators] -- bandwidth, IOPS, latency -- by deploying NVMe SSDs," He explained. "NVMe also places lower demand on the CPU on a per-IOPS basis, which means that the CPU resources can be freed up to process other tasks, so there's additional benefit there beyond the storage I/O performance that is provided by NVMe."
NVMe devices are very close in price to traditional SSDs and can deliver up to 4 GBps with PCIe and M.2 buses. "This makes them a clear winner from a value and performance point of view, especially for hyper-converged solutions where the goal is to pack as much performance into each server at the lowest cost possible," Pruen advised.
Drawbacks and challenges
Rob Commins, senior director of commercial and enterprise brand marketing at Western Digital, sees high cost as a major NVMe SSD storage drawback.
"Currently, large deployments are cost-prohibitive, but this is exactly what we saw when flash was first catching on," he said. "The cost of NVMe has already begun to decline, and as the technology matures, this trend will only accelerate, meaning this drawback will gradually disappear entirely."
Organizations primarily deploy NVMe over a PCIe fabric, which is usually internal to the host system.
"To take advantage of NVMe in a large scale-out shared environment, you need NVMe over Fabrics, similar to SCSI over FC SAN [fiber channel storage area network], for example," He said. "This is a challenge today because this is where you have different vendors advocating different 'over Fabrics' technologies, and the supplier count within each technology is limited."
Providing redundancy across NVMe SSD storage devices can also be challenging. "Today, most RAID controllers don't support NVMe, so users must look to software RAID -- which may not be available from the installed OS -- or find systems that support node-to-node synchronous mirroring that will keep the system running even if a drive failure brings down a whole server," Pruen said.
The outlook
Given NVMe's multiple benefits, it's probable that NVMe SSD storage will dominate the SSD market within a few years.
"One of the NVMe protocol's advantages is how well it integrates into the modern world of remote memory and networking access," said Kirill Shoikhet, chief architect at Excelero, an NVMe-over-Fabrics array startup. "This integration allows for vendors to provide a much wider range of value-adds compared to traditional SSDs."
Like most other system components, NVMe SSD storage will gradually progress from a premium product to a mainstream offering. "Some vendors will specialize in performance and quality, while others will gravitate to the bottom of the price spectrum," Hinton predicted. "Don't be surprised to see top-end implementations involve a pair of PCIe Gen3 slots, and low-end solutions gravitate to BGA [ball grid array] board-mounted designs."
Traditional hybrid storage architectures, which combine tiers of different media, withstood the initial flash tsunami by incorporating SSDs into a much larger cache layer than was possible using RAM.
"I think [vendors] won't be able to continue with the almost 30-year-old approaches in the new world ruled by NVMe devices," Shoikhet said. "I expect to see significant architecture changes completing the flash revolution sweeping the data centers."
"Over the next two years, there's going to be a land grab of sorts, and NVMe will be a given in enterprise storage, just like flash is today," Cobb said. "The difference in benefits will be based around implementation."
