About Fast Reload
The fast reload feature enables you to reboot the switch faster than with the reload command. You can also use fast reload to upgrade the software on the switch.
During a fast reload, the NXOS software image that runs on the CPU reloads the new image and runs it without a CPU or firmware reset. Although traffic is briefly disrupted during a fast reload, this feature enables the switch to reload faster than during a cold reboot.
You can use fast reload in a non-interruptive mode, which runs the installation process without any prompts, or with BGP graceful restart for BGP-compatible peers.