What is SR-IOV?

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Cherokee touches on it 70-740, but I'm not quite grasping the concept.

@John-DeWilde said in What is SR-IOV?:

Cherokee touches on it 70-740, but I'm not quite grasping the concept.

SR-IOV represents Single Root I/O Virtualization:

"SR-IOV enables network traffic to bypass the software switch layer of the Hyper-V virtualization stack. Because the VF is assigned to a child partition, the network traffic flows directly between the VF and child partition. As a result, the I/O overhead in the software emulation layer is diminished and achieves network performance that is nearly the same performance as in nonvirtualized environments." from Microsoft Docs

Remember that when using virtualization, everything is virtualized. This included the network adapter along with the all the hardware that helps a VM function as a "server" or "pc" in that environment. When it comes to the NIC virtualization this is helpful because you may have many VMs but only a single NIC on a machine. Each VM needs it's own NIC...so they virtualize it--or "shares" the NIC.

The paragraph I quoted, essentially tells us the the SR-IOV gives that VM the ability to "by-pass" this software switch (virtualized switch). Why? to allow that VM to achieve the network performance that is nearly the same as if it's not a VM sharing the NIC.

@Ronnie-Wong Thank you. Does each vm believe that the nic is assigned exclusively to itself?

@John-DeWilde,

It a sense, they each have a virtual MAC address and "believes" as if it's not virtualized. So they do not "sense" they are not directly attached to the hardware. But we, as users, would experience the latency to that VM. Sometimes, performance isn't affected dramatically but let's take a VM SQL server that is "hit" by every one in our system about every other moment of the work day. This is a good scenario that we might take advantage of the SR-IOV.