A few years ago, the Japanese government’s New Energy and Industrial Technology Development Organization (NEDO) allocated funds to develop green data center technologies. With the goal of achieving up to 40% savings in overall energy consumption, several Japanese companies are developing an optical interface for their enterprise SSDs. And at this year’s FMS, Kioxia showed off its optical interface.
For this demonstration, Kioxia took its existing CM7 Enterprise SSD and created an optical interface for it. A PCIe card with built-in optics, developed by Kyocera, is installed in the server slot. The optical interface allows data to be transmitted over long distances (in the demonstration it was 40m, but Kioxia promises cable lengths of up to 100m in the future). This allows storage to be stored in a separate room, with minimal cooling requirements compared to a CPU and GPU rack. Separating different server components will become an option as very high-bandwidth interfaces such as PCIe 7.0 (at 128 GT/s) emerge.
The optical SSD demonstration showed a small loss in IOPS performance but a significant advantage in latency metrics over the shipping company’s SSD over a copper network link. It is clear that there are advantages in cabling requirements and maintaining signal integrity over optical links.
As a proof-of-concept demonstration, we see the need for an industry standards approach if this is to gain acceptance across data center vendors. The PCI-SIG Optical Workgroup will need to get its act together soon to create a standards-based approach to this problem.
