Windows Server 2012 R2

Windows Server 2012 R2 is the server counterpart of Windows 8.1. It replaces Windows Server 2012 and was replaced by Windows Server 2016.

This is the first version of Windows Server to drop support for processors without the CMPXCHG16b, PrefetchW and LAHF/SAHF instructions.

Editions
There are three editions of this operating system: Essentials, Standard and Datacenter. As with Windows Server 2012, the Datacenter and Standard editions are feature identical, varying only based on licensing (particularly licensing of Hyper-V VMs). The Essentials edition has the same features as the Datacenter and Standard products, with some restrictions.

Changes

 * Automated Tiering: Storage Spaces stores most frequently accessed files on fastest physical media.
 * Deduplication for VHD: Reduces the storage space for VHD files with largely similar contents by storing the similar contents only once.
 * Windows PowerShell v4, which now includes a Desired State Configuration (DSC) feature.
 * Web Application Reverse Proxy.
 * Integrated Office 365 support.
 * The return of the Start button.