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OEM Licensing: How many licenses do I need?


Let’s review a few things we’ve learned from the first two OEM Licensing Friday blogs, “Back to the basics” and “Dive into Licensing:

  • All servers running an instance (physical or virtual) of Microsoft® Windows Server must have a valid Windows Server license assigned.
  • HP OEM Reseller Option Kit (ROK) is a great way for our reseller partners to easily sell and deploy Windows Server Operating Systems (OS) on HP ProLiant servers.
  • OEM Licenses must be delivered as part of the server sale with the Certificate of Authenticity (COA) affixed.


** If you  missed the past two blogs in this series, please read them now to learn more about HP OEM ROK Licensing for Windows Server: “OEM Licensing: Back to the basics” and “OEM Licensing: Dive into Licensing”.


Today we will look at Base Licenses and Additional/Additive licenses and how to determine the total number of licenses required.


With Windows Server 2012, a per-processor licensing structure was introduced. This new licensing structure allows customers to acquire the precise number of licenses needed for both the physical processors and VMs on their servers while also providing a single, familiar, and easy-to-track method of both tracking licenses and providing proof of license compliance for audits.


Base OEM licenses for Windows Server 2012 and 2012 R2 Standard edition support 2 physical processors and 2 Virtual Machines (VMs). You may “stack” more than one Standard license on a server in order to support additional physical processors and/or concurrent VMs. Likewise, you may “stack” more than one Datacenter license on a server to support additional physical processors (Datacenter provides support for unlimited VMs). When buying “stacked” OEM licenses direct from HP, HP will fulfill the second and subsequent licenses with an additive or additional license, which does not include redundant media.


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Determining the number of Windows Server licenses needed

If you know you need licensing for more than 2 processors, but need help calculating the total number of Microsoft Windows Server licenses needed for the server solution… you’ve come to the right place for help!


For the Datacenter Edition of Windows Server 2012 and Windows Server 2012 R2, simply divide the number of physical processors by 2 (don’t forget to round up!), and that’s the number of licenses you need (remember, each Datacenter license supports 2 physical processors and an unlimited number of concurrent VMs).


For the Standard Edition of Windows Server 2012 or Windows Server 2012 R2, the number of licenses needed depends on the number of physical processors on the server AND the maximum number of virtual server instances you will be running concurrently.

There are 3 steps to calculate the number Windows Server standard licenses needed for each server:

  1. Calculate how many licenses are required for the physical processor needs (using the same steps listed above
  2. Count the total number of VMs needed for the server, divide by two and round up to the nearest whole number.
  3. The larger of the two numbers—the physical processor licensing requirements and VM requirements—determines the number of total licenses required.


NOTE: although pricing for a Standard license stacking may seem less expensive at time of server purchase, consider both current needs and future expansion – it may turn out that Datacenter is the best purchasing decision in the long-run.  In general, Datacenter is usually the best long-term investment if you will need 10 or more concurrent VMs.




Join us next week for the next edition of our OEM Licensing Friday blog and, if you haven’t already, be sure to join our Coffee Coaching communities on Facebook, Twitter, YouTube, and LinkedIn!

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