Jay Keating, vice president of managed services at the Andover Mass.-based company, said that the firm has installed and is in production with a pair of Xsigo I/O Directors, essentially InfiniBand switches, plus additional management capabilities. NaviSite connects its VMware servers to the Xsigo switch, which it uses to assign virtual network interfaces (vNICs) and Fibre Channel virtual host bus adapters (vHBAs) to individual VMware virtual machines (VMs). The vNICs and vHBAs can be created on the fly without a server reboot and can be migrated among physical servers while maintaining MAC addresses and World Wide Names, Xsigo reports.
Rather than purchase separate Ethernet and Fibre Channel cards for a server, NaviSite now purchases an InfiniBand host channel adapter (HCA) "from just about anyone," Keating explained. The server is then connected to the Xsigo I/O Director, which then connects out to NaviSite's existing Ethernet network and Fibre Channel storage fabrics.
With 10 Gbit of bandwidth, a single InfiniBand connection has ample room to carry both Ethernet and Fibre Channel traffic. And compared with outfitting connecting servers directly to the IP and storage networks, "we're spending about a third in the cost of cabling," Keating said. "It's not insignificant."
Cabling costs just the beginning
But NaviSite wasn't just looking to reduce its cabling costs. Had it been, "we probably would have gone with someone with more credibility," Keating said, such as Cisco Systems, whose VFrame product offers similar cable consolidation benefits, he said. What Keating particularly liked about the Xsigo I/O Director was its ability to dynamically allocate I/O resources between VMs.
Over the years, NaviSite's managed services business has begun to rely increasingly on virtualization. "Now, every managed service you could have bought before [on a physical box] you can buy virtualized," Keating said. Rather than overprovision a server for I/O, as in the days before Xsigo, "you buy the platform you need today," he said. And Xsigo helps NaviSite "make sure users are getting exactly the right amount of I/O that they are paying for."
The exact dollar amount NaviSite saves with this management flexibility is unclear. "It's harder for me to quantify how much greater density I get using Xsigo," Keating said. But he added that it "feels to us like a savings."
Going forward, Keating said NaviSite had plans to integrate the Xsigo system with a self-service customer portal the firm is developing on top of Xen. Instead of having to manually add or remove virtual I/O resources from a VM, the resources can be assigned dynamically based on policy.
I/O virtualization takes off
I/O virtualization is a hot topic these days, with several companies trying their hand at the technology, said Greg Schulz, senior analyst at the Stillwater, Minn.-based StorageIO Group. Other than Xsigo, vendors in the space include Cisco with its VFrame, QLogic Corp. and 3Leaf Systems.
When married with server virtualization, I/O virtualization's benefit becomes much greater than just reducing the number of cables and expansion slots required in a server, Schulz said. It's also about the flexibility and the reusability of the resources. "In the VMware world, you're often consolidating operating systems that rely on different technologies -- for example, iSCSI and Fibre Channel," he said. But if your I/O connections are virtual, you can conceivably consolidate workloads on the same physical machine that rely on different I/O protocols, he postulated.
But while seemingly attractive, the Xsigo technology is still in its infancy, he warned. One question potential customers might have, for example, is "Which operating systems are supported at any one time?" If Xsigo is emulating Fibre Channel HBAs, for example, "QLogic or Emulex might not be too pleased that they're emulating their HBAs."
Another variable is 10 Gbps Ethernet, which might also emerge as a valid I/O consolidation transport, Schulz said. For now, it can transport only iSCSI and network-attached storage traffic, "but as Fibre Channel over Ethernet (FCoE) starts to get rolled out, all of a sudden, the story starts to change."
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