Fujitsu, a leading server maker, and Intel Corp. during the Fujitsu Forum in Munich demonstrated the world’s first server with Intel optical PCIe Express (OPCIe) external interconnection that relies on Intel Silicon Photonics technology.
Fujitsu demonstrated the world's first server solution featuring an Intel optical PCIe Express-based server connected to an external expansion box containing additional compute and storage nodes using Intel Silicon Photonics. The solution demonstrated opportunities that Intel Silicon Photonics can bring to the data center with the ability to connect separate boxes with compute or storage nodes in a way that appears to the CPU to be on the main motherboard while actually being fully virtualized.
Rack based servers, especially 1u and 2u servers are space and power constrained. Sometimes OEMs and end users want to add additional capabilities such as more storage and CPUs to these servers but are limited because there is simply not enough space for these components or because packing too many components too close to each other increases the heat density and prevents the system from being able to cool the components.
The solution to the power and space density problems is to locate the storage and compute components on a remote blade or tray in a way that they appear to the CPU to be on the main motherboard. The other way to do this is to have a pool of hard drives managed by a second server – but this approach requires messages be sent between the two servers and this adds latency – which is bad. It is possible to do this with copper cables; however the distance the copper cables can span is limited due to electro-magnetic interference (EMI). One could use amplifiers and signal conditioners but these obviously add power and cost. Additionally PCI Express cables can be heavy and bulky (up to whopping 20lbs/9kg). By contrast, Intel MXC optical cable carries 10x the bandwidth and weighs one to two pounds depending on length.
Fujitsu took two standard Primergy RX200 servers and added an Intel Silicon Photonics module into each along with an Intel designed FPGA [field programmable gate array]. The FPGA did the necessary signal conditioning to make PCI Express “optical friendly”. Using Intel Silicon Photonics Fujitsu engineers managed to send PCI Express protocol optically through an MXC connector to an expansion box. In this expansion box was several solid state disks (SSD) and Xeon Phi co-processors as well as Silicon Photonics module along with the FPGA to make PCI Express optical friendly. The SSD’s and Xeon Phi’s appeared to the RX200 server as if they were on the motherboard. With photons traveling at 186 000 miles per second the extra latency of travelling down a few meters of cable cannot reliably be measured (it can be calculated to be ~5ns/meter or 5 billionths of a second), according to Victor Krutul, the director of marketing for the silicon photonics operation at Intel.
Fujitsu’s approach provides three key benefits:
- Fujitsu was able to increase the storage capacity of the server because they now were able to utilize the additional disk drives in the expansion box. The number of drives is determined by the physical size of the box.
- Fujitsu was able to increase the effective CPU capacity of the Xeon E5’s in the RX200 server because the Xeon E5’s could now utilize the CPU capacity of the Xeon Phi co-processors. In a standard 1u rack it would be hard if not impossible to incorporate Xeon Phi’s.
- The third benefit is the cooling. Putting an SSD or co-processor into an expansion box allows them to burn more power because the cooling is divided between the fans in the 1U rack and those in the expansion box.
At present it is unclear when Fujitsu and Intel plan to commercialize solutions based on MXC optical interconnection technologies.