With data center virtualization, "it's not enough to give a server a fat pipe" such as 10 Gigabit Ethernet, says Dave Zabrowski, CEO of Neterion. The pipe itself has to be virtualized--that is, it must be able to perform at near line rates for virtualized applications, up to 10 Gbps.

Neterion's X3100 adapter provides that I/O virtualization. Zabrowski calls it "the missing piece of virtualization to data centers."

The SR-IOV standard was devised to give makers of network interface cards and host bus adapters a common way to virtualize I/O on x86 instruction set servers. The PCI-SIG is the industry association that came up with the standard.

Many adapter suppliers are expected to eventually enter the 10 Gigabit Ethernet field with similar devices that also support SR-IOV. But Neterion is the first vendor to combine high-end Ethernet capacity with leading-edge virtualization.

Instead of a single I/O channel, the Neterion X3100 Series adapter lets multiple virtual machines share a single NIC and still be guaranteed that each virtualized application has access to a full-bore, 10 Gig Ethernet I/O route when needed. The routes can be dynamically reallocated to meet application demand based on quality-of-service requirements.

The Neterion X3100 can generate 17 I/O paths, though the actual number for VM use is 16. The 17th channel was added for I/O management instructions.

The ability to virtualize I/O lifts one of the constraints on server virtualization in the data center. As servers are virtualized and the number of applications per server increases, so does the potential for I/O contention.

Data center administrators are trying to balance virtual machine workloads by putting virtualized applications with different I/O requirements on the same server. If, in addition to virtualizing applications, administrators can virtualize server I/O, it becomes easier to put more and more demanding applications on each physical server without worrying about I/O needs. To date, applications with high I/O demands have not been virtualized, largely for performance reasons.

Neterion supplies host bus adapters for servers produced by Fujitsu Computer Products of America, Hewlett-Packard, IBM, and Sun Microsystems. Gigabit Ethernet is a common device specification today; 10 Gigabit Ethernet is likely to become standard over the next 10 years, Zabrowski says.

The X3100 adapters support VMware's NetQueue on ESX 3.5, and the company plans to support other hypervisors soon. Look for street prices starting at about $1,000.