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ESXi: Change vmnic / vmhba numbering

If you change your hardware configuration without reinstalling your hypervisor you might run into an issue with the nic or hba port numbering. The ESXi host writes the PCI bus to vmnic mapping to a special configuration file. If you change the pci slot from your dual port nic for example you end up with 2 new vmnics.

The configuration file is located at /etc/vmware/esx.conf

Change vmnic numberingPlease note that this method is not supported by VMware!

1. Open up the console (SSH or Tech Support Mode)
2. Backup your configuration

cp /etc/vmware/esx.conf /etc/vmware/esx.conf.old

3. Open esx.conf with an editor

vi /etc/vmware/esx.conf

4. Search for "vmnic" (press /vmnic<ENTER>)

5. Identify your physical nics. This could be done by many ways. You can use CDP if supported by your physical switch. Or just plug in a cable and see which port comes up. The number between the colons is the PCI Bus ID. Refer to your hardware vendors documentation to find out which Bus belongs to your PCI Slot. In most cases its just ascending to the PCI Slot written to the chasis.

6. Change the vmnic label. (Move the cursor to the label, press r for "replace" and enter the new number)

7. Search again for "vmnic" (press /vmnic<ENTER>) until you find something like this

8. This is the MAC address configuration which has to be consistent to the vmnic numbering made above. The easiest way is to just delete these lines, as they are getting recreated after a reboot. Move the cursor to the line an press dd for each line you want to delete.

9. Press <ESC> :wq <ENTER> to save the configuration.

10. Reboot your ESXi Host.

Verify the configuration using the vSphere Client:

Changing the vmhba numbering is the same. Just search the esx.conf for vmhba. There is just one entry per port.

3 thoughts on “ESXi: Change vmnic / vmhba numbering”

  1. Great stuff, thanks.

    I'd moved a NIC as one of my nodes wasn't configured the same as the other three when shipped from Dell (nic was in a different slot for some reason - didn;t notice until after I had installed ESXi unfortunately) - once moved and I rebooted the server the vmnic numbering had incremented as it was detected as a new card. This allowed me to make it the same as the others again.

    Many thanks

  2. Pingback: ESXI home lab, one the way to the VCP. |

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