I was recently made aware of this article in which the author, Karim Elatov, had successfully demonstrated the use of a Sonnett Thunderbolt 2 to 10 Gigabit Ethernet Adapter with ESXi running on an Apple Mac Mini. As far as I am aware of, this may be the first public confirmation that such a device would work with ESXi, not to mention having it functional on the Mac Mini. I know in past years, there have been unconfirmed reports on various forums mentioning a Thunderbolt to 10GbE solution that works with ESXi but it was unclear on whether custom drivers were needed or if it would even work with newer versions of ESXi.
This topic has been popular amongst our customers who virtualize Apple MacOS on vSphere. In fact, several years back I had written an article on Thunderbolt Storage for ESXi, which includes a number of solutions that our customers have implemented to provide remote storage for their vSphere infrastructure running on either an Apple XServe, Mac Pro or Mac Mini. Questions around a functional Thunderbolt to 10GbE has definitely been asked about, but I had never heard from any customer who have had a successful story to share, at least until now.
From Karim's post, it looks like he was able to get this working using ESXi 6.0 but it was unclear if there was anything he needed to do to get the device recognized. I reached out to Karim and he was able to confirm that the Thunderbolt device was recognized by ESXi without any additional driver installation. In fact, if you look at this console output on his blog, you will see that it simply uses the inbox Intel ixgbe driver. I had also asked if Karim tried this with the latest version of ESXi, which is currently at 6.5 Update 1. Karim was kind enough to perform one additional test for me which was to confirm the device would still work with the latest ESXi release, which you can see for yourself in the screenshot below.
UPDATE (02/04/19) - Chad Moon recently shared his experiences on getting 10GbE support with an Intel NUC using the OWC Mercury Helios 3, Thunderbolt3 to PCIe expansion enclosure