Well, it's not always as simple as 'how many systems' even when you're talking about just an operating system. There's licensing based on cores and/or sockets. Then there's licensing for virtual machines.
Oracle was really nasty in some of the licensing scenarios, IIRC. If you ran an Oracle DB on an unlicensed platform in a VM (such as VMWare), then when you got audited, you needed to pay for how many cores/sockets were in the physical server, rather than just how much CPU your VM was using.
Oracle was really nasty in some of the licensing scenarios, IIRC. If you ran an Oracle DB on an unlicensed platform in a VM (such as VMWare), then when you got audited, you needed to pay for how many cores/sockets were in the physical server, rather than just how much CPU your VM was using.