Just when you thought PCIe 4.0 x4 SSD's were fast with up to 8 GB/s of sequential read speed, PCIe 5.0 drives have emerged on the horizon that could come with up to 16 GB/s speeds.
Silicon Motion said this week that it would start sampling its enterprise-grade SSD controllers with a PCIe Gen 5.0 interface in the second half of next year, which means that they will debut commercially in 2022. This is one of the first times that an SSD controller maker has mentioned a chip with a PCIe 5.0 interface, and even though the controller will debut in the server space, models for consumers will inevitably follow.
No Rush for PCIe 5.0 SSDs?
The PCIe 5.0 interface will increase data transfer speeds to 32 GT/s per lane, which will increase the total bandwidth provided by a PCIe x16 slot to ~64 GB/s, whereas a PCIe x4 slot can transfer up to ~16 GB/s.
Increased transfer rates will be particularly beneficial for various bandwidth-hungry applications, like servers, high-end storage subsystems, and accelerators. Using the PCIe Gen 5 physical layer, various next-gen platforms will also support CXL and Gen-Z protocols designed specifically to connect CPUs with various accelerators and maintain memory and cache coherency at low latencies.
The first platforms to support a PCIe 5.0 interface are Intel's 12th-Gen Alder Lake CPUs for client PCs, which are expected to debut in the second half of 2021, as well as the company's 4th Generation Xeon Scalable 'Sapphire Rapids' for data centers and supercomputers that is projected to launch in early 2022. In addition to PCIe 5.0, Sapphire Rapids will also support the CXL 1.1 protocol.
So far, several companies have already announced the availability of PCIe 5.0 controllers and PHY IP, and some have demonstrated interoperability of their CXL-enabled PCIe 5.0 solutions with Intel's Sapphire Rapids or verification equipment, whereas Microchip even announced its PCIe 5.0 retimers and switches.
However, as numerous developers of SSD controllers and platforms introduced their PCIe 4.0 platforms for servers in the second half of last year, including Kioxia, Microchip, Silicon Motion, SK Hynix, it doesn't seem like they will roll out any new enterprise-grade solutions in the foreseeable future. Of course, some companies tend to introduce next-gen SSDs ahead of competitors, but it does not look like there will be too many PCIe 5.0-supporting enterprise drives available next year, so SMI will be on time with its PCIe Gen 5 controller.
The PCIe Gen 5 specification was finalized in mid-2019, around the same time when the first PCIe 4.0-supporting platforms, SSDs, and GPUs were launched. Back then, some thought that the PCIe 4.0 interface will have a short lifespan (because PCIe 5.0 was 'already there') and will not become truly popular particularly in the data center space, as back then, the only server platform to feature PCIe 4.0 lanes was AMD's EPYC 7002-series 'Rome' that was not truly popular at the time. As it turns out, while PCIe 5.0 will debut later this year, it does not look that it will immediately replace PCIe 4.0.
SMI Mentions First PCIe 5.0 SSD Controller
"With our new PCIe Gen5 enterprise SSD controllers sampling in the second half of next year, we are not expecting our enterprise SSD controller to be a material contributor to our $1 billion sales objective," said Wallace Kuo, chief executive of Silicon Motion, during a conference call with analysts and investors (via The Motley Fool). "We are planning on material enterprise SSD controller sales contribution only after 2023."
Silicon Motion is a newbie on the market of enterprise SSD controllers. The company first entered China's enterprise SSD market in 2015 after acquiring Shannon Systems, a supplier of enterprise-grade PCIe SSD and storage arrays to Chinese hyperscalers. So far, SMI's enterprise SSD business has not really taken off and represents a fraction of its revenue. Still, the company clearly wants to be a part of the datacenter megatrend, so it will continue to invest in enterprise storage solutions.
"We are excited about enterprise-grade PCIe Gen5 controller, which we will have taped out early next year and sample in the second half of 2022," said Kou. "We believe this will bring us a big momentum in coming to enterprise."
The chief executive of Silicon Motion naturally did not touch upon technical specifications of the company's upcoming PCIe 5.0 enterprise SSD controller, but its latest SM8266 SoC supports NVMe 1.4, three dual-core Arm Cortex-R5 complexes, 16 NAND channels, and configurable LDPC ECC.
