I have created a new datacenter and added my ESXi 5.5 hosts to it, using their IP-address. Now I would like to change to using Hostname. Is it possible to change the name without any downtime to the host (i.e. not put it into maintenance, remove from inventory and then add it back)?
Yes, you can remove from inventory while VMs are running on the host and add back in using the host name instead of the IP address.
My Suggestion would be to plan a downtime on Esxi hosts and re-add them using their FQDN. Please note that doing so will result in host losing their data related to Performance.
I see there is a script written & shared in below website which will allow us to change the display name with just a disconnect and reconnect tasks involved which will not cause any impact to host performance data. Please test the script in LAB before implementing it in production environment.
I have found the answer in KB1014030. The procedure has to be done using the Vsphere Client. I was unable to make this work in the WebClient since I was not allowed to rename when reconnecting.