We want to run two VMs (virtual machines) that are dedicated to Concert. .We have been discussing the configuration of the VMs and we wanted to run the idea of separating the IVR and EMS processes into different VMs. Would this be advisable? Our ideas is that the EMS can handle all authentications without being blocked by the IVR. Also, if, for whatever reason, the EMS fails, it won’t bring down the IVR, and vice versa. 

If we go this route, is there anything specific we need to do in order to accomplish this? Do you have any special instructions that we can use? 
This is a highly specialized requirement and should only be done after consultation with Clear-Com 
It involves a small change within the ivr.conf configuration file.  Here is the procedure:
1. Uninstall the IVR service on the VM running the EMS service
2. Install the IVR service on your 2nd VM
3. Stop the IVR service (service ivr stop)
4. Edit the ivr.conf configuration file as follows:
Location: /usr/local/clearcom/concert/bin/ivr.conf
Set the key “ems_server” key to the IP address of the VM running the EMS service (be sure to retain the :6002 port designation after the IP)
For example:  Old - ems_server=127.0.0.1:6002New - ems_server=10.10.1.165:6002
5. Restart the EMS service on the 1st VM and then start the IVR service on the 2nd VM
All of your clients should reconnect once both the ESM and IVR services has been started.