This is one of the mainframe's key selling points. Not that I am implying z/VM is user friendly.
But instead of managing a fleet of x86 servers, switches, routers, storage boxes (you may need a few of those), all liable to fail without warning, you have an exquisitely built datacenter that fits in half-a-dozen 19" racks (counting 2 for storage) where redundancy, failover, and easy maintenance are built-in at the hardware level.
