I have to say, this is one of the more interesting challenges that I have come across in quite some time. A user was looking for assistance after they accidentally disabled the vmkusb module, which is the USB driver for ESXi and allows it to communicate with USB devices that are connected to the system.
The vmkusb module also plays a very critical role if you have ESXi installed on a USB device, as the driver is required for proper functionality such as being able to save the ESXi state and configurations to the USB device. So what happens when you disable the vmkusb module and you reboot the ESXi host, which is also installed on a USB device?
Well, everything continues to work including VMs since ESXi by design runs in memory after the initial boot from the USB device. However, any configuration changes made after that is lost after a system reboot including the attempt to re-enable the vmkusb module since ESXi is unable save any of the settings to the USB device. Fortunately, I was able to help the user out as I had a few ideas on how we could fully recover from this type of scenario and hence the blog post.
Hopefully a lesson can be learned here, do not make changes or disable things that you are not familiar with 🙂