Mac OS X, Windows, and Linux Virtualization Rules
Just as you can’t take your $29 copy of Lion Server and install it on every Mac in your office, you also don’t have the right to install a copy on an unlimited number of virtual machines. When running guest operating systems in virtual machines, you have to abide by the software licensing agreements that Apple and Microsoft (and others) make you agree to when you install their software.
Apple’s virtualization rules for Mac OS X
Apple changed its virtualization rules with Lion. The good news is that it allowed Mac OS X clients — specifically, Mac OS X 10.7 — to be run in a virtual machine.
The bad news is that Apple restricted the number of versions of Lion you can run on each Mac: You cannot run more than two virtual machines containing Lion and Lion Server on one Mac. One copy of Lion or Lion Server entitles you to run it in two virtual machines per Mac, in addition to using it for the host OS.
For Mac OS X 10.5 and 10.6, you can run only the Server version, not the client, in a virtual machine. And each license entitles you to run only one copy in a virtual machine. But there’s no limit on the numbers of copies you can run on one Mac.
You can run three Leopard or Snow Leopard Server virtual machines running on one Mac, as long as you own two copies of Mac OS X Server and use separate serial numbers on each in order to not violate the license agreements.
You can also have a Mac mix older and newer versions of Mac OS X Server in virtual machines. In this case, you use the licensing restrictions of each version.
For example, you could have one Mac running two Lion Server virtual machines and four Snow Leopard Server virtual machines. You’d have to own one copy of Lion Server and four licenses of Snow Leopard Server. Of course, your Mac can also be running virtual machines containing Windows and Linux.
For any version of Mac OS X, the virtual machine must be running on an Apple Mac. So unfortunately, you can’t virtualize Mac OS X in your data center along with your Windows and Linux virtual machines.
Microsoft’s rules for Windows and others’ rules for Linux
Microsoft is happy to let you run Windows Server in virtual machines on any hardware, including your Macs. But you still have to pay for the licenses. If you buy a single-license copy of Windows Server, you get to run it in one virtual machine.
If, however, your organization runs a lot of Windows Server virtual machines, it may own a Microsoft Windows Server Datacenter Edition license, which includes the ability to run an unlimited number of virtual machines running Windows Server — in which case you can clone away. Check with your IT department if you work in a big organization.
The situation varies for Linux. Open source operating systems can be replicated without fees, but don’t confuse them with some commercial Linux operating systems that do have license fees.