That’s a mouthful. I’ve been having a hard time figuring out how to successfully transfer images to the Standby ASA’s flash from the Active’s CLI. Finally figured it out. Here’s the syntax:
failover exec standby copy /noconfirm tftp://{ip address}/{file name} disk0:/{file name}
Without the /noconfirm it’ll fail. You also need a standby ip address on the interface facing the tftp server and I haven’t confirmed this but I think it might also need to be on the same subnet. I’m still having some trouble with a situation where the standby ASA would have to reach another subnet.