ESXi 6.0 and network performance issue

April 8, 2016 9 By Allan Kjaer

I have had a few customers that had a performance issue, when running in certain combination:

  • ESXi 6.0
  • Windows 2012 / Windows 8 or later
  • Virtual hardware 11 / Compatibility 6.0 or later
  • VMXNET3 network card (this is part of newer VMware Tools) or later

There is VMware KB on this, that have a solution:

I have used the alternative solution:

You can disable LRO/RSC for all virtual machines on an ESXi host using:

esxcli system settings advanced set -o /Net/Vmxnet3SwLRO -i 0
esxcli system settings advanced set -o /Net/Vmxnet3HwLRO -i 0

Note:This will disable LRO for all virtual machines on the ESXi host. Virtual machines will need to be powered off and back on or vmotioned between hosts for the changes to take effect.

Notes (March 6, 2017):

The Article says that this has to do with Jumbo frames, I have see this in configuration without jumbo frames.

It also says SQL, I have see this with other application.

It also says it solved in 6.0 Update 2, But I have see the problem after upgrading to this, with Veeam Proxy server take backup thru NBD. The solution is the same.

Notes (February 23 , 2018):

I have had some customers that is running 6.5 Update 1, that is seeing this problem again, the solution is the same, here is a script for setting this setting on all hosts i a vCenter.

$vcenter = Connect-viserver <vCenter server>

$vmhosts = get-vmhost

foreach ($vmhost in $vmhosts) {
        Get-AdvancedSetting -Entity $vmhost -Name "Net.Vmxnet3SwLRO" | Set-AdvancedSetting -Value "0" -Confirm:$false
        Get-AdvancedSetting -Entity $vmhost -Name "Net.Vmxnet3HwLRO" | Set-AdvancedSetting -Value "0" -Confirm:$false
Disconnect-viserver $vcenter

Use of this at your own risk. remember that the VM’s need to be rebooted or vMotioned to another host to take affect.

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