Change MTU on physical ports without downTime

[SCharchouf]

is there a way to change the MTU for physical NICs [vmnic] without downtime?

The issue is that MTU 9000 was enabled on vmkernel and not enabled on physical ports which is not recommended and such kind of configuration impact performance and I'm able to identify a high % of dropped packets

[LucD · Accepted solution]

Afaik you can change the MTU without the need of a reboot.

$mtuSize = 1500

Get-VMHost | Get-VMHostNetworkAdapter -VMKernel |

where{$_.Mtu -ne $mtuSize} |

Set-VMHostNetworkAdapter -Mtu $mtuSize -Confirm:$false

[SCharchouf]

Thanks Luc but this is to change MTU on VMKernel and my question is related to physical vmnic ports

shall I try something like this:

$mtuSize = 9000

Get-VMHost | Get-VMHostNetworkAdapter -Physical |

Where-Object{$_.Mtu -ne $mtuSize} |

Set-VMHostNetworkAdapter -Mtu $mtuSize -Confirm:$false >>

can I get output for the vmnic into a file before change and got the config after change?

[LucD]

I'm not sure exactly what you are trying to do.

Afaik, you can set the MTU on a vmkernel or on a switch (VSS and VDS).

When done on a switch, all uplinks used by that switch will be set to that MTU.

I never set the MTU directly on a 'physical' vmnic.

[SCharchouf]

I'm trying to change the MTU on physicall ports because if it's noit set like vmkernel it create a lot of dropped packets

[LucD]

I don't know how to do that, and I don't know if that is even possible

[SCharchouf]

it's Ok I got it 🙂

In fact, the MTU of the physical port changes once the vmkernels are in a vDS 😊