Installing Ubuntu OpenStack requires at least five machines with two disks, two of which have two network interfaces (NICs). Install Ubuntu Server on one of the machines with two interfaces.
Why do I need two disks? What if I have 5 machines with 2TB capacity each but on a single disk? Would this setup not work i:e http://www.ubuntu.com/download/cloud/install-ubuntu-openstack? Why do we need 2 interfaces on two machines? I understand for one machine, one interface connects to the internet and the second to the local network. But why do we need 2 interfaces for the second machine?