I have noticed this a couple times now. digging through the logs, it looks like the host decided to become unresponsive:
2017-08-24 12:09:05,365-04 INFO [org.ovirt.engine.core.bll.VdsEventListener] (org.ovirt.thread.pool-6-thread-5) [56defee2] ResourceManager::vdsNotResponding entered for Host 'a1bf54c1-2890-4aae-a23d-c83ea2c664d2', 'Host IP'
Caused by: java.net.ConnectException: Connection refused
There is a lot more, but I thought dropping it into a pastebin would be better:
It looks like the host stopped responding somehow but I can't quite tell how. Any advice or input would be greatly appreciated!