Big iron has been a staple of enterprise data processing for half a century, but is the mainframe era coming to an end? On one side there's the virtualisation-driven view that such machines are relics of a bygone technology era and should be replaced or migrated to virtual, cloud servers as soon as possible. On the other side are the advocates and engineers who believe that these big, robust computers still have a role to play in today's enterprise. Who's right? We take a look at the future of mainframes in the enterprise.