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Server 2012 R2, dVMQ for VMs and NIC team, what happens with MPIO iSCSI SAN configuration

    Question

  • Hi

    I am in the process of configuring a Hyper-V host which is connecting to a SAN via MPIO iSCSI, the server has 4 x physical NICs, 2 of which are connected to the SAN and two for VM traffic in a team.

    With the server having 48 vCPUs can I assign all (24 in sum of queues) to the NICs connecting to VM's or do I need to leave some vCPUs and configure them for the SAN traffic NICs?

    I have read up on VMQs but cannot find any reference to setting RSS or VMQ for MPIO iSCSI connections?

    If I only need to consider VMQ on the VM NICs I was going to use or can I even use 12 as a MaxProcessors?

    Set-NetAdapterVmq -Name Intel Eth1 -BaseProcessorNumber 2 -MaxProcessors 12
    
    Set-NetAdapterVmq -Name Intel Eth3 -BaseProcessorNumber 26 -MaxProcessors 12

    This would mean I leave 0 free for management OS and they don't overlap, but Eth3 would only have 10 MaxProcessors.

    If I need RSS I need to probably follow this article

    https://charbelnemnom.com/2015/04/the-available-processor-sets-of-the-underlying-physical-nics-belonging-to-the-lbfo-team-nic-are-not-configured-correctly-hyperv-vmq-rss-lbfo/

    Any help/advice appreciated.

    Sunday, April 09, 2017 7:27 PM

Answers

  • VMQ is inbound-only, and only applies to virtual machine vNICs. It is never applicable to host iSCSI traffic, MPIO or otherwise.

    RSS would only function if your SAN happens to support it. If it does support it, then for it to be useful it would also need to 1) be able to send enough traffic to overwhelm CPU0:core0, 2) have a habit of sending enough data to overwhelm CPU0:core0. Unless you're using Pentium 4s, that's an unlikely scenario.

    Configure VMQ and be done with it.


    Eric Siron
    Altaro Hyper-V Blog
    I am an independent contributor, not an Altaro employee. I accept all responsibility for the content of my posts. You accept all responsibility for any actions that you take based on the content of my posts.

    • Marked as answer by ChrisJKnights Monday, April 10, 2017 9:04 AM
    Sunday, April 09, 2017 10:05 PM

All replies

  • VMQ is inbound-only, and only applies to virtual machine vNICs. It is never applicable to host iSCSI traffic, MPIO or otherwise.

    RSS would only function if your SAN happens to support it. If it does support it, then for it to be useful it would also need to 1) be able to send enough traffic to overwhelm CPU0:core0, 2) have a habit of sending enough data to overwhelm CPU0:core0. Unless you're using Pentium 4s, that's an unlikely scenario.

    Configure VMQ and be done with it.


    Eric Siron
    Altaro Hyper-V Blog
    I am an independent contributor, not an Altaro employee. I accept all responsibility for the content of my posts. You accept all responsibility for any actions that you take based on the content of my posts.

    • Marked as answer by ChrisJKnights Monday, April 10, 2017 9:04 AM
    Sunday, April 09, 2017 10:05 PM
  • Thanks for that, really appreciated.

    Does the VMQ configuration look correct or should I be using MaxProcessorNumber as well?

    Set-NetAdapterVmq -Name "Intel Eth1" -BaseProcessorNumber 2 -MaxProcessors 12 -MaxProcessorNumber 24
    
    Set-NetAdapterVmq -Name "Intel Eth3" -BaseProcessorNumber 26 -MaxProcessors 12 -MaxProcessorNumber 48

    In the past I have always used smaller processors and 1GB NICs nothing like to spec of the server I am currently installing so I have never gone above 4/6 for MaxProcessors before.

    Many thanks

    Monday, April 10, 2017 9:13 AM
  • The original setting that you were using looked fine to me. I don't think the 2 max settings work together like that anyway.

    Eric Siron
    Altaro Hyper-V Blog
    I am an independent contributor, not an Altaro employee. I accept all responsibility for the content of my posts. You accept all responsibility for any actions that you take based on the content of my posts.

    Monday, April 10, 2017 12:51 PM