When customers ask you what the differences are between the Windows Server 2008 R2 Standard and Enterprise editions in terms of licensing rights, make sure you're ready with an answer. With these types of questions in mind, a critical aspect of a solution provider's job when attempting to sell Windows Server 2008 R2 is to know the details of each Windows Server 2008 R2 edition.
Read this FAQ with Hyper-V expert Greg Shields and learn the role that client access licenses play in Windows Server 2008 R2 and how Hyper-V licensing is handled in each edition. There is also information on how to approach running virtual instances in different Windows Server 2008 R2 editions.
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With Microsoft products, a CAL is required to allow clients to connect to servers and make use of services. CALs come in many forms and those used to connect to Windows typically come in either per-user or per-device mode. Windows Server 2008 R2 CALs are not required for the host computer, that which runs Hyper-V services. CALs are, however, required for any virtual machines (VMs) that reside on top of that host.
Hyper-V and Hyper-V Server have very similar names and look like very similar products at first glance. But these two products are very different in terms of licensing. Hyper-V is a role that can be added to an instance of the Windows Server 2008 R2 operating system (OS). You must have a functioning and licensed copy of the Windows Server 2008 R2 OS in order to use Hyper-V.
You can download Hyper-V Server for free, and it's a standalone product with no licensing requirements. Hyper-V Server is often confused with Hyper-V because Hyper-V Server arrives as a feature-restricted instance of Windows Server 2008 R2 Server Core Edition. That feature-restricted instance is intended to run Hyper-V services only (including add-on services such as host clustering).
With the release of Windows Server 2008 R2, Microsoft announced that each one running a physical OS instance can also run a number of virtual OS instances. The number of additional licenses gained depends on the OS edition. Windows Server 2008 Standard Edition adds rights to run one virtual OS instance. Windows Server 2008 Enterprise Edition adds rights to run four virtual OS instances. Windows Server 2008 Datacenter Edition has special rights that allow a running instance to run unlimited virtual instances. These licensing terms have not changed with the release of Windows Server 2008 R2.
Not necessarily. Windows Server 2008 R2 Standard and Enterprise Editions are both licensed on a per-instance basis, which means that a powerful computer and a less-powerful computer can be licensed for the same cost. Windows Server 2008 R2 Datacenter Edition is licensed on a per-physical processor basis. This change means that servers with greater numbers of physical processors require a more expensive license.
Recall that Windows Server 2008 R2 Enterprise Edition adds four virtual licenses to every physical license, while Datacenter Edition adds unlimited licenses. Recognize also that more concurrently running virtual machines will require more processors to ensure good performance. Thus, a tradeoff between concurrently-running VMs and physical processors is necessary in order to find the best answer. Microsoft provides two different Windows Server virtualization calculators that can assist in determining which license makes the best sense.
I get asked this very important question all the time because many businesses are unknowingly violating Microsoft's licensing terms. Rather than paraphrase Microsoft's licensing terms, allow me to quote from Microsoft's Windows Server 2008 R2 Licensing FAQ page:
"The rights to run the four instances are assigned to the licensed server, and all the instances can run only on the licensed server. You may not move your rights to run an additional two instances to another server. However, if you have another server that is licensed for Windows Server 2008 R2 Enterprise or Datacenter, you may move the two workloads to that server and run them on that server provided that by running the additional instances you do not exceed the licensed capacity of the new server (one with Windows Server Standard, four with Windows Server 2008 R2 Enterprise, and unlimited with Windows Server 2008 R2 Datacenter)."
Allow me to quote again from another question on the same FAQ page. This second answer deals with the situation where a company wants to run a fifth VM atop a physical host:
"With a license for Windows Server 2008 R2 Enterprise, you may run up to four instances of the software in virtual operating system environments. If you want to run a fifth instance in a virtual operating system environment, you must acquire and assign an additional license to that server. It may be more economical to license the server with Windows Server 2008 R2 Datacenter or 'step up' your Enterprise license to Windows Server 2008 R2 Datacenter."
Windows Server 2008 R2 editions overview
Windows Server 2008 R2 edition comparison by server role
Windows Server 2008 R2 editions and system requirements
About the author
Greg Shields, MVP, vExpert, is a partner with Concentrated Technology. Get more of Greg's tips and tricks at www.concentratedtech.com.
This was first published in November 2010