vSphere 5.1 and later supports Single Root I/O Virtualization (SR-IOV). SR-IOV is a specification that allows a single Peripheral Component Interconnect Express (PCIe) physical device under a single root port to appear to be multiple separate physical devices to the hypervisor or the guest operating system.

SR-IOV uses physical functions (PFs) and virtual functions (VFs) to manage global functions for the SR-IOV devices. PFs are full PCIe functions that include the SR-IOV Extended Capability which is used to configure and manage the SR-IOV functionality. It is possible to configure or control PCIe devices using PFs, and the PF has full ability to move data in and out of the device. VFs are lightweight PCIe functions that contain all the resources necessary for data movement but have a carefully minimized set of configuration resources.

SR-IOV-enabled PCIe devices present multiple instances of themselves to the guest OS instance and hypervisor. The number of virtual functions presented depends on the device. For SR-IOV-enabled PCIe devices to function, you must have the appropriate BIOS and hardware support, as well as SR-IOV support in the guest driver or hypervisor instance.