Those who choose the Hot Standby option will have a backup Mac mini to be used in case of a hardware failure of their own mini. While the customer's Mac mini is being repaired, we'll provide another machine that can be used. The standby Mac mini has a brand new install of the OS of your choice. It's most useful if you have a bootable backup of your machine. In that case,we can move the external drive to the standby mini, boot from it, and you're up and running. Nice and simple.