A company has a Windows Server 2012 R2 server that has the Hyper-V role installed. The server has a single
processor and a single 10-gigabit network interfacecard (NIC). 12 virtual machines (VMs) run on the server.
You need to configure Hyper-V to allow higher network throughput and reduce processing overhead related to
network operations. What should you do?
A.
Run the Windows PowerShell command Set-VMNetworkAdapter -VmqWeight 0 on the VMs.
B.
In Hyper-V Manager, disable the protected networkoption for all NICs on the VMs.
C.
in Hyper-V Manager, enable the Single Root I/O Virtualization (SR-IOV) option on the VMs.
D.
Disable Internet Protocol security (IPsec) task offloading on the VMs.
Why not answer c, by enable sr-iov?
I don’t think disable vmq will meet the requirement “You need to configure Hyper-V to allow higher network throughput and reduce processing overhead related to network “
VMQ provides improved networking performance to the management operating system as a whole rather than to a specific virtual machine. For the best results, treat queues as a scarce, carefully managed resource. Because queues are allocated to virtual machines on a first-come, first-served basis, making all virtual machines eligible for a queue may result in some queues being given to virtual machines with light traffic instead of those with heavier traffic. Enable VMQ only for those virtual machines with the heaviest inbound traffic. Because VMQ primarily improves receive-side performance, providing queues for virtual machines that receive the most packets provides the most benefit to overall management operating system performance.
Bandwidth isn’t necessarily the key benefit of SR-IOV in Hyper-V. The VM Bus can saturate a 10Gb link, but that amount of traffic generates enough CPU load to occupy one core. So if low CPU utilization is a key design goal, SR-IOV is the key. If latency is a critical aspect, SR-IOV gives performance close to a physical NIC.
On a host where you expect a lot of incoming VM traffic, Dynamic Virtual Machine Queue (dVMQ) distributes the traffic into queues for each VM based on MAC address hashes. It also distributes the interrupts across CPU cores.
I would go with SR-iov: the use of virtual functions bypasses the vmbus = reduces the processing overhead (1 of the requirements).
I have to go with SR-IOV, too: http://msdn.microsoft.com/en-us/library/windows/hardware/hh440148%28v=vs.85%29.aspx
I would also have to go with answer C.
“This is identical in functionality to VMQWeight in Windows Server 2008 R2, and expresses a desire for a hardware offload, not a guarantee. A positive number between 1 and 100 is “on”, and 0 is “off”. We do not, in Windows Server “8” use a relative weighting system. All numbers between 1 and 100 mean the same. This design allows us to add ‘weighting’ functionality in the future without needing to change APIs.”
http://blogs.technet.com/b/jhoward/archive/2012/03/16/everything-you-wanted-to-know-about-sr-iov-in-hyper-v-part-5.aspx
John Howard’s article confirms that issuing a VmqWeight 0 to a VM will express the desire to NOT use SR-IOV for the VM.
If the value was any number between 1 and 100, that would be a good answer.
That rules out the answer A. Again, C is the only to go.
Answer is C
What is SR-IOV
Requires support in network adapter
Provides Direct Memory Access to virtual machines
Increases network throughput
Reduces network latency
Reduces CPU overhead on the Hyper-V server
Virtual machine bypasses virtual switch
Supports Live Migration, even when different SR_IOV adapters are used
=====================================================================
Why the answer is NOT “A”:
-VmqWeight
Specifies whether virtual machine queue (VMQ) is to be enabled on the virtual network adapter. . The relative weight describes the affinity of the virtual network adapter to use VMQ. The range of value is from 0 through 100. Specify 0 to disable VMQ on the virtual network adapte
Dynamic Virtual Machine Queues (D-VMQ) for Hyper-V. VMQ is a hardware virtualization technology that increases the efficiency of network processing when packets are received on a Hyper-V host. This optimizes the networking performance of the host and reduces overhead as packets are delivered to virtual machines.
Without VMQ technology and RSS, a majority of the network processing would burden CPU0 and would ultimately limit the scale of the solution.
I agree
SR-IOV
http://technet.microsoft.com/en-us/library/jj721570.aspx
Enable Single-root I/O virtualization (offload setting): With single-root I/O virtualization (SR-IOV), a network adapter can be assigned directly to a virtual machine. The use of SR-IOV maximizes network throughput while minimizing network latency and minimizing the CPU overhead that is required to process network traffic.
Answer is A.
C is wrong as the NIC must support SR-IOV. Not every NIC supports SR-IOV.
I’m wondering how wrong you guys think …
Let me correct, C can also be as we have only one CPU … damn questions!
Okay, let’s take C!
The correct answer is C, not A. The requirements are to allow higher network throughput and to reduce processing overhead related to network operations. Answer A expresses the desire for a hardware offload, but it is not a guarantee, as other have already pointed out. Answer C enables network traffic to bypass the software switch layer of the virtualization stack. This diminishes the I/O overhead in the software emulation layer, which results in network performance that is almost identical to that of a non-virtualized environment.
The best answer is A.
Exp.
You can connect a
virtual switch to different networks, and based on this connection, you can create a private, internal, or
external virtual switch. If supported by server hardware, you can also use features such as single root I/O
virtualization (SR-IOV) and Dynamic Virtual Machine Queue, which enable higher network throughput
and lower CPU utilization.
answer c is correct. Remember question is asking allow higher network throughput and reduce processing overhead .
VMQ is using cpu depending on number of cores .However,SR-IOV reduces CPU as well as increases network throughput
Answer is A. SR-IOV needs required hardware what is not mentioned.
https://support.microsoft.com/en-us/kb/2902166
Also if there is a broadcom chipset there is a knowledgebase article telling you to disable to queue.
The answer is C too because the command VmqWeight is used for Specifies whether virtual machine queue (VMQ) is to be enabled on the virtual network adapter. . The relative weight describes the affinity of the virtual network adapter to use VMQ. The range of value is from 0 through 100. Specify 0 to disable VMQ on the virtual network adapter.
Read this https://technet.microsoft.com/en-us/library/hh848457.aspx
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Good luck to everybody!
This article is interesting https://blogs.msdn.microsoft.com/altr/2014/09/14/hyper-v-virtual-switch-performance-dynamic-vmq/
C is right answer
Wmq is disabled with the value 0