VMWare VMotion: do doing a VMotion on a virtualised Windows server changes it's MAC address?

Posted on 2012-04-12
Medium Priority
Last Modified: 2012-08-13
My guess is that is does not change the MAC address but just to be safe:
Can someone confirm me that doing a VMotion on a virutalisated Windows server do not change it's MAC address?

One of my server is a FlexLM server and as you know, FlexLM licensing requires/incorporate the MAC address of the server. So, on a physical server, every time I would want to install FlexLM to another server I would need to re-register it with them. And if the network card fails on a physical server, I would also need to re-register.
But with visualization, if I need to do a maintenance on the blade that holds my visualized windows server, I do a vmotion and move all vm running on that blade to other blades and that must not impact FlexLM.
Question by:SigSupport

Accepted Solution

Geodash earned 1600 total points
ID: 37839345
No, the MAC should not change. It will change if you clone it

The MAC address is written in the vmx file (also with the VM UUID).

So vMotion or a host migration does not move this file and for this reason does not change it.

A datastore migration will move the file, but also will keep as-as (it's a move operation).


But a clone operation is a copy plus a modification of the vmx file (to have different MAC address and unique UUID).

For this reason if you make a manually copy and then add the vmx to the inventory and power-on the VM you will prompt for a message asking if you have copy or moved the VM.

Sorry, that was taken from here -


You can force it to keep the current MAC by looking here as well -

LVL 126

Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 400 total points
ID: 37839383

The configuration of the VM does not change, only the Host running the VM changes.

Author Closing Comment

ID: 37842440
Thanks guys.

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