I'm on a vSphere4 course at the momnet and we've just covered dvSwitches.
Our instructor is of the opinion that if you reboot your vCenter server, your dvSwitch goes "missing" for the duration of the reboot - so all your VMs lose network connectivity.
I don't think this is the case, as dvSwitches are a high-end bit of functionality, and this seems like a very big single point of failure - surely the configuration is managed by vCenter, but it's cached in some way by the hosts and they will continue to function - but changes cannot be made without the vCenter server being available?
Can anyone clarify what happens to a dvSwitch and the traffic passing over it when vCenter is rebooted?