Depends on your boot mode you like to boot, you can load images on USB to Copy into flash - always suggest to Boot from flash.
I never tried it, but you could try copy kickstart and system image to USB disk and try below example :
boot kickstart USB:/n7000-s2-<kickstart image>.bin sup-1
boot system USB:/n7000-s2-<system image>.bin sup-1
if no image available on USB it gets into ROMMON Mode.
thanks for your reply, so basically if a usb is plugged in as the router boots up and this router is not configured to boot from usb the router should boot up normally, correct?
the issue i am facing is that i need to reboot a nexus 7k and during that time a usb drive will be plugged in as i have stored license and config backup on there i just don't want the router to go into rommode or just stop booting as there is a usb drive plugged in.
Thanks for your help
I do not believe Nexus has the ability to boot like Pc or any other device boot from USB until unless you have boot variable, it will not boot from USB.