Windows Server 2008 R2 Overview

It is the first 64-bit–only operating system released from Microsoft. Enhancements include new functionality for Active Directory, new virtualization and management features, version 7.5 of the Internet Information Services (IIS) web server and support for up to 256 logical processors.

There are seven editions: Foundation, Standard, Enterprise, Datacenter, Web, HPC Server and Itanium, as well as Windows Storage Server 2008 R2.

Licensing of Windows Server 2008 R2 remains generally consistent with Windows Server 2008 licensing, with a few highlights:

Windows Server 2008 R2 Access Licensing

Windows Server is primarily licensed using a Server + CAL model or a Processor + CAL model. Windows Server Standard and Enterprise editions are licensed using the Server + CAL model, while Windows Server Datacenter and Windows Server for Itanium-Based Systems editions are licensed using the Processor + CAL model. Under both models, the CAL that accesses the instance of Windows Server must be equivalent or higher in version than the server being accessed. An exception to this rule was introduced with Windows Server 2008 and continued with Windows Server 2008 R2. Under that exception, customers must still license the appropriate CAL version to access the version of the server software running in each virtual operating system environment, but they are not required to upgrade their CALs based on the version of Windows Server that is running in the physical operating system environment. In this scenario, the Hyper-V server role must be the only role running in the physical operating system environment.

A Windows Server 2008 Client Access License (CAL) must be purchased for every user or device that accesses or uses the Windows Server 2008 or Windows Server 2008 R2 server software, except under the following circumstances:

• If the instances of the server software are accessed only through the Internet, without access being authenticated or otherwise individually identified by the server software or through any other means

• If the server software being accessed is Windows Web Server 2008, Windows Web Server 2008 R2, Windows Server 2008 Foundation, or Windows Server 2008 R2 Foundation

• If external users are accessing the instances of the server software and a Windows Server 2008 External Connector license for each server being accessed has been acquired

• If up to two devices or users are accessing the instances of the server software for the purpose of administering those instances

• If Windows Server 2008 R2 serves solely as a virtualization host (CALs for the appropriate edition of Windows Server running in the virtual machine(s) are still required).