The basics of Microsoft server licensing, models, and operating system environments
Editor’s Note: This was originally published on October 28, 2016, by TechSoup.org following changes to Microsoft’s Server Licensing Models
This page provides an overview of Microsoft server licensing. You can also visit Microsoft's Product Licensing search page for detailed licensing information on individual products and product families, including current Product Use Rights (PUR) documents.
Licensing Models
Understanding licensing requirements will help you plan your server implementation. This section provides a brief overview of the four basic licensing models for Microsoft servers.
Per Core/CAL
The Per Core/CAL model includes core-based server licenses and Client Access Licenses (CALs) for users or devices with connections to the servers. Windows Server Standard and Datacenter are examples of products that use this model.
The Windows Server products also offer optional external connector licenses for connecting people who are not employees or on-site contractors (usually providing web-based access).
The core-based server license products in this model are valid for two processor cores. For these products, most organizations will need to request enough server license products to meet Microsoft's minimum requirements and to cover all the cores on their server.
For more information on Windows Server Licensing, view our Guide to Windows Server Licensing.
Server/CAL
The Server/CAL models include server licenses and Client Access Licenses (CALs) for users or devices with connections to the servers. Exchange Server Standard and Enterprise and SQL Server (Server/CAL) are examples of products that use this model.
The server license products in this model provide one license for an entire server. For these products, most organizations will need to only request one server license product as well as any CALs they might need.
Per Core
The Per Core model includes only core-based server licenses. Client Access Licenses (CALs) are not required. BizTalk Server and SQL Server (Core-Based) are examples of products that use this model.
The core-based server license products in this model are valid for two processor cores. For these products, most organizations will need to request enough server license products to meet Microsoft's minimum requirements and to cover all the cores on their server.
Management Servers
The Management Servers model includes server management licenses (MLs) for the servers that are being managed and client MLs for the non-server operating system environments (OSEs) that are being managed. Licenses to run the server software are included with the MLs. System Center products use this model.
Similar to the core-based server license products, the server ML products in this model are valid for two processor cores. For these products, most organizations will need to request enough server ML products to meet Microsoft's minimum requirements and to cover all the cores on the server being managed.
The client MLs in this model provide one license for a client device OSEs or user and are not core-based. For these products, most organizations will need to only request one client ML product for each managed OSE or user on the client device.
Licensing Operating System Environments
Server operating systems and server applications can run in either physical or virtual Operating System Environments (OSEs). When your servers or other devices have multiple OSEs, you should check the OSE licensing requirements carefully.
For example, many Microsoft server licenses can be used for only a single OSE. When this is the case, if the server operating system or application is installed in more than one environment on a single server computer, a separate license is required for each environment. However, other Microsoft server licenses can be used in both the physical OSE and in one or more virtual environments.
For more detailed licensing information on individual products and product families Microsoft's Product Licensing Search page.