If you’re trying to set the time on a brand new out of box Cisco Nexus 5500 and you get the message “Setting clock from CLI is not allowed in this VDC.”, it’s because the clock protocol is set to ntp, even though you didn’t configure NTP. Go into config and type “clock protocol none”, and then it will let you set the time.
Then, when you’ve finished the config, set up NTP!
And while you’re at it, this page from Cisco is awesome for troubleshooting VPC