NEC has announced an extension of their ExpEther PCIe over Ethernet switch technology that will come to virtualize I/O resources so that they can be shared simultaneously between servers. The new IOV solution adds scalability, better quality of service while delivering on the promise of I/O on-demand, reducing capital expenses by half and power consumption by 30 percent. By combining PCIe and Ethernet, NEC makes I/O Virtualization (IOV) available and relevant to the mass data center market.
While "Fiber Chanel over Ethernet is only for storage, and InfiniBand needs PC or InfiniBand adapters and special driver software," says Takashi Yoshikawa, Research Manager for NEC. They felt that using the ubiquitous Ethernet standard would bring IOV to the table for everyone. IOV was introduced by the PCI special interest group when it was realized that dense server virtualization could cause an I/O bottleneck, significantly impacting the performance of I/O intensive applications. Instead, IOV bypasses the inundated hypervisor and enables VMs to share direct access to a host's I/O resources. The I/O cards are moved out of the server into a card-cage, which is connected to the server via a single high-bandwidth interconnect.
NEC has used a system which in effect converts their top of rack (ToR) switch into this IOV card cage. Details are slim, as we could only receive answers to a single e-mail from Japanese office, but from our read it looks like the NEC approach is similar to the one proposed by Xsigo, one of the first IOV vendors. Replacing the ToR switch bring some impressive numbers to the equation. Eliminating the ToR switch and reducing the NICs per server reduce your capex budget, but also dramatically cuts energy costs. Xsigo claims, for example, that implementing their I/O director in a 500 server data center will have the environmental impact of taking 425 cars off the road.
However, replacing the ToR switch isn't the accepted strategy of all IoV vendors. Aprius Inc, for example, argues that it is a mistake to force the removal of the ToR switch, "Switches do many things that IOV doesn't and shouldn't do, " says Varun Nagaraj, CEO of Aprius. He argues that introducing their IOV gateway to complement the ToR switch will bring tremendous advantages to the data center, above and beyond cost and power savings. IOV can enable the rapid introduction of new I/O into an existing data center, significantly improve the ROI of upgrading I/O and make server systems far more flexible, especially by sharing expensive I/O resources such as solid state storage.
Meanwhile, NEC is confident that they have backed the right horse with Ethernet instead of another, perhaps faster, interconnect. "FCoE requires new FCoE compliant Ethernet switches, FCoE compliant FC-HBA and also modification in the transport layer," says Yoshikawa. The use of Ethernet certainly makes their system more compatible than some competitors and will promises time and cost savings on retraining staff for new protocols.
