VMTools Upgrade Behavior

We have had issues where upgrading VMtools causes the existing NIC to be replaced by another NIC and all settings are lost.

This can happen, when the network interface, changes PCI slot in the virtual machine, and the effect as you describe is the removing of the current network interface, and the insertion of a new network interface.

We are running ESXi 5.5 U3b and upgrading tools from various versions to version 10.

I think you may be getting confused here. There are two changes being discussed here

1. updating VMware Tools.
2. changing and upgrading the virtual machine version to version 10.

There is NO real reason to rush and upgrade VMware Tools or Upgrade virtual machine version. Upgrading the virtual machine version just gives you the benefit of using newer virtual machine version 10 features.

Although recommended to be on the latest version of VMware Tools compatible with the Host OS, it's not an absolute MUST DO!

So which order did you do these changes, BECAUSE order is important.

1. VMware Tools Upgrade first.
2. Upgrade Virtual machine version second.

and always have a backup before you start, so you can rollback, any changes to production machines.

Hi Andrew,

Thanks for your response.

I was actually referring to Tools version 10240 here. However, I do have the same  question about expected behavior of the vNICs after a hardware version upgrade (we are going from either v4 or v7 to v10), and found multiple warnings about ensuring tools are upgraded first, so we've been doing that.

I can find articles about both Tools and Hardware upgrades causing NICs to be replaced, thus losing configuration, but nothing about predicting this result, except the issue about upgrading hardware before tools. My goal is to get proactive so the team knows what result to expect.

That's exactly what VMware support said. They have almost no details and suggested backing up the config before upgrading.

Unfortunately, it's the OS which does it plug and play.