I/O Virtualization

I/O virtualization is a complimentary solution for server and storage virtualization, which aims to reduce the management complexity of physical connections in and out of virtual hosts. Virtualized data center clusters will have multiple networking connections to LAN and SAN, and virtualizing the network avoids the extra complexity associated with it. While I/O virtualization reduces the management complexity, in order to maintain high productivity and scalability one should pay attention to other characteristics of the network being virtualized.

Offloading the network virtualization from the VMM (virtual machine manager, e.g. Hypervisor) to a smart networking adapter, not only reduces the CPU overhead associated with the virtualization management, but also increases the performance capability of the virtual machines (or guest OSs) and can provide the native performance capabilities to them.

The PCISIG has standards in place to help simplify I/O virtualization. The most interesting solution is Single Root I/O virtualization (SR-IOV). SR-IOV allows a smart adapter to create multiple virtual adapters (virtual functions) for a given physical server. The virtual adapters can be assigned directly to a virtual machine (VM) instead of relying on the VMM to manage everything.

SR-IOV provides a standard mechanism for devices to advertise their ability to be simultaneously shared among multiple virtual machines. SR-IOV allows the partitioning of PCI functions into many virtual interfaces for the purpose of sharing the resources of a PCI device in a virtual environment.

Mellanox interconnect solutions provide full SR-IOV support while adding the required scalability and high throughput capabilities to effectively support multiple virtual machines on a single physical server. With Mellanox 10GigE or 40Gb/s InfiniBand solutions, each of the virtual machines can get the needed bandwidth allocation to ensure highest productivity and performance, just as if it was a physical server. 

Gilad Shainer
Director of Technical Marketing
gilad@mellanox.com