Hi,
You can monitor the listening ports of the Policy Server. To illustrate quickly,
on Linux, you can run :
let's say Policy Server IP 192.168.1.1
# nmap 192.168.1.1 -p 44441-44444
If the Policy Server is up and running, you'll get the output as :
PORT STATE SERVICE
44441/tcp open unknown
44442/tcp open coldfusion-auth
44443/tcp open coldfusion-auth
44444/tcp open unknown
Nmap done: 1 IP address (1 host up) scanned in 0.07 seconds
So depending of the loadbalancer you run, you might also check those ports availability. Add monitoring of the port 44445, if you have configured the Policy Server as central oneview monitoring server too.
I hope that helps,
Best Regards,
Patrick