While performing some VM migrations I encountered a strange anomaly – ghost port groups appearing under the Network section in the vSphere client. Below we can see 4 port groups but there should only be 2:
So what preceded this strange happening? Well, the VMs I was working on were being migrated from an older ESX 4.1 standalone host to a shiny new ESXi 5.1 standalone host. The important factor here is that I had to upgrade VMware Tools and the Virtual Hardware version to the latest versions once the VMs had been moved to the new ESXi 5.1 host. Being a good boy scout I followed the official process detailed here on VMware’s site, which recommended taking a snapshot of each VM prior to upgrading VMware Tools and the Virtual Hardware version. After the snapshot was taken I changed the port groups of each VM to match the new port groups. This was when I noticed this strange occurrence. A quick check of the virtual Network adapters confirmed that there were only 2 networks and not 4:
Once the upgrade work had been completed and we deleted the snapshots those ghost port groups disappeared:
The moral of the story is taking a snapshot of the VM and then changing the port groups while the snapshot is still active will show both the old and new port groups until the snapshot is removed.