When a PC or server boots from the external USB disk the mirror is on, and there is a DHCP server, the mirror becomes available immediately, through http and rsync. It uses i386 architecture, so both 64- and 32-bit systems will run. The local disks of the machine will not be harmed. The mirror will try to sync itself between 21:03 and 06:03 local time.

If there is no DHCP server, the machine won't get an IP number. In that case, /etc/network/interfaces has to be symlinked to interfaces.static (and edited if necessary), and the network interface has to be brought up.

It is also possible to take the disk from its USB enclosure, mount it in a PC or server, and boot from it. Whether this works depends - I suspect - on whether the BIOS of the host agrees on disk geometry with the machine I used to create the disk.