Updating the firmware on CMC will require a reboot. Without rebooting, the update cannot be even initiated. It will patch both active and standby CMC at the same time.
OME uses RACADM tool to perform update on CMC controllers. An update command is sent to CMC along w/ the path for the payload (f/w image). If the update command returned success (0), then OME keeps polling every 2 minutes to check the firmware update status.
When the firmware update is completed, OME gets a return status as success which is relayed back to the UI.
Thanks,
Raj Shresta