Last year, Xsigo and Dell announced a relationship where the server vendor would resell the IOV supplier's equipment. The move was expected to position Dell at the forefront of virtualization. However, difficulties in integrating IOV into servers cleanly and advances in bus and IO performance have done little to advance IOV outside of relatively niche situations like high performance computing, data modeling and animation rendering.
"As our customers continue down their path of IT simplification, they look to Dell to help them with all aspects of their virtual infrastructure," said Rick Becker, vice president of Software and Solutions, Dell Product Group. IO virtualization was Dell's next step down the virtualization route, as a valuable offering for their customers.
Vendors rushed into fill the market. Xsigo was followed by Virtensys, NextIO, Neterion and Aprius. Regardless of the player, the technology shared some commonalities. All IOV technologies are based loosely on the underlying principle that each physical server has one or two cable connections to a rack mounted card cage, into which all the I/O resources like networking and storage are plugged. Each virtual machine (VM) is subsequently allocated a dedicated virtual NIC and virtual HBA, giving them dedicated I/O access. This process allows the VMs to improve performance by bypassing the hypervisor when attempting to gain access to IO resources.
Vendors vary in their choice of protocols to the card cage, some preferring PCIe while others selecting InfiniBand or Ethernet. They also differed in features of the card-cage and the number of available interconnections. Until now, the various IOV vendors have been ironing out their solutions and placing their bets on the right architecture, as the data center market is not yet in need of this technology.
A year later, Dell has become a little less positive about its Xsigo deal. "Xsigo has advantages and disadvantages," says John VonVoros, virtualization product manager at Dell. "They're a little nichey and require a lot of additional work [to support the adapter drivers and the Infiniband infrastructure]." What happened between Dell and Xsigo underscores some of challenges faced by IOV vendors in general. The technology that burst onto the scene at the end of 2008 was supposed to extend the virtualization wave that took over the network and server to the I/O. IOV was expected to enable interconnectivity redundancy and drastically reduce the network card and cabling infrastructure of the data center and supposedly lead significant power savings.