Mainframe hardware isn't reliable though. It maybe more reliable, but no hardware is reliable. What you call reliable is implemented by an architecture that let

Mainframe hardware isn't reliable though. It maybe more reliable, but no hardware is reliable. What you call reliable is implemented by an architecture that lets the system route around hardware damage. The difference is that a mainframe is a mostly closed box where you preselect what hardware components are wired together, while a cloud computing type system is an open system where you can dynamically rearchitect it.