I don't believe there is anything more detailed than that there is however a very good session (again old) on how KMS operates and it hasn't functionally changed as fair as I'm aware.
I've cut into the section you will be interested in.
https://youtu.be/I5gR_dVqfz0?t=653
- What happens if vCenter is offline/ failed?
- Depends, on boot the hosts are given the keys by vCenter. The keys are stored in ESXi memory so as long as you do not reboot the hosts, your VMs will be fine. If it comes up and vCenter is not available it will not be able to get it's host keys to then get the VM keys therefore that particular host cannot access the VMs on storage.
- What happens if 1 KMS is offline Failed?
- It fails over to the next KMS in the list
- What happens if both KMS are offline/failed?
- Again depends if you reboot the hosts, the keys are stored in the hosts memory and are lost on reboot
