What IBM's mainframes do directly, and what the sales guys do push aggressively given half a chance, is what's now called "private cloud": hosting virtual-machi

What IBM's mainframes do directly, and what the sales guys do push aggressively given half a chance, is what's now called "private cloud": hosting virtual-machine instances which can be quickly provisioned or shut down, on hardware owned or rented by the customer. This is what Amazon reportedly just sold to the CIA, for example. As to experience, the mainframe guys have been doing "private cloud" on a small scale since the early 1970s, via VM/370 and its successors. Current versions can easily host dozens of VMs on a single hardware machine, running several guest OSes, including Linux.