Fujitsu shows servers using light, lasers to transfer data

Fujitsu moves storage, high-speed co-processor out of Primergy RX200 and into an expansion box connected via fiber optics


The server maker showed two Primergy RX200 servers connected to expansion boxes via an optical cable, with light used to transfer data between the systems. Light is considered a faster way to transfer data than copper wire.

The demonstration was made at the Fujitsu Forum being held in Munich this week, and the optical data transfer hardware is based on Intel's silicon photonics technology. The technology is being demonstrated as a way to show how high-speed connections with fiber optical cables allows processing and storage units to be decoupled from servers and moved to separate boxes. The Primergy expansion boxes have solid-state drives and Intel Xeon Phi co-processors, which would go directly into expansion slots in the servers.

The optical connection is based on Intel's OPCI-Express protocol, which is the optical version of the PCI-Express specification. Use of light and lasers helps transfer data at fast speeds over longer distances compared to traditional PCI-Express connections, and helps move components further away CPUs. As a results, servers could be smaller, more storage and co-processors can be crammed into dedicated boxes, and power and cooling costs could be reduced.

The servers and expansion devices have transfer modules and FPGAs (field programmable gate arrays) that make the systems ready for optics. The optical cables uss 68G bps (bits per second) of bandwidth, though data transfers could theoretically touch 100G bps. The FPGAs, which emulate the OPCI-Express protocol, are limited to eight lanes of PCI-Express Gen3.

For the demonstration, the optical cables were 10 meters in length. However, data transfers could reach 25G bps if cables are extended to 800 meters, said Victor Krutul, director of marketing for the Silicon Photonics Operation at Intel, in a paper sent to IDG News Service detailing the Fujitsu demonstration.

Silicon photonics has been a long-term research project for Intel, and the company starting introducing protocols and cables this year. The company also demonstrated a custom server from Quanta with the optical technology.

Everyone knows there are bandwidth limitations to copper, and the longer the distance the more critical an issue it becomes, said Dean McCarron, principal analyst at Mercury Research.

"Optical is the shoo-in for the next interconnect," McCarron said.

Optical technology is used for wider telecom networks, but now the goal is to put it inside computers and in data centers as a possible replacement to technology reliant on copper wires.

"The motivation is much longer term," McCarron said.

The technology is still being demonstrated and could be a few years away from actual implementation. Over time, the optical cables and related technologies such as modules will get cheaper. Intel is already making the technology on silicon, so they are trying to bring the overall cost down, McCarron said.

Intel is also using optical technology for data transfers in technologies like Thunderbolt, which is also available on copper cables for Macs and PCs. But the Thunderbolt optical cables remain more expensive than copper cables.

Intel also has more work to do on integrating optical technology in servers, like getting rid of the modules and bringing the optical cables closer to the CPUs.

Long term, Intel wants to put optical interfaces on the chip instead of on motherboards, McCarron said.


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