After an upgrade to VMware vSphere 5.5 on a Dell PowerEdge R710, I’ve got strange occasion issues, where the hosts got completly disconnected from vCenter (with the ESXi/ESX host’s status as Not Responding or Disconnected in vCenter Server) and there was no way to reconnect, also after restarting the management services. Locking in the ESXi console those kind of errors where notable: Bootbank cannot be found at path ‘/bootbank’. The only temporally solution was power-off the VMs and restart the host. But the issue can randomly came back.