The sentinel service now reports metrics about encountered errors here: https://viceroy.corp.google.com/chromeos/sentinel?hostname=chromeos-server26&heatmap=False&topstreams=5&duration=1d&refresh=-1

Unrecoverable errors: Currently, there are 23 unknown hosts, 3 afe hosts that need some human attention to get fixed.

Recoverable errors: Sentinel is consistently fixing some 300 host labels and some 60 host labels each day across the fleet.
That's too high.

Someone needs to go look at what these errors are and fix them.

--> deputy for triaging.