"host currently has no management network redundancy" warning in Virtual Center 2.5:

this warning happened after I created a HA cluster with 2 ESX hosts. they are
basically white boxes I run development VMs on. after the cluster creation, one
of the hosts had this in the summary display. This turned out to be a
configuration issue with the network adapters. VC 2.5 expects the Service
Console attached to at least 2 nics to avaid isolation response.

to add a user on ESX to have access to console (shell, ssh):

1) login to console with root
2) adduser -g users -d /home/ -s /bin/bash