Windows Server 2008 R2 build 7601.17514

Windows Server 2008 R2 build 7601.17514 is the official RTM build of Windows Server 2008 R2 Service Pack 1 that was released to manufacturing on 9 February 2011 with the build being released to MSDN and TechNet subscribers as well as Volume License customers a week later on 16 February 2011. On 22 February 2011, it became generally available for download via Windows Update and the Microsoft Download Center alongside its client counterpart.

This release would later be used as the base for Windows MultiPoint Server 2011, Windows Home Server 2011 and Windows Small Business Server 2011 Essentials.

It is the last Service Pack to be released by Microsoft for a Windows Server release before Service Packs were dropped starting with the release of Windows Server 2012.

New features and changes
The Service Pack 1 release implements various significant changes to the base operating system, with improvements made towards various components such as DirectAccess and Failover Clustering. Hardware support has also been improved, with the OS now able to fully utilize CPUs implementing the Advanced Vector Extensions (AVX) CPU instruction set and improved support for Advanced Format disk drives that fall under the 512 emulation (512e) category.

The RemoteFX functionality was added, bringing 3D hardware acceleration support over to Hyper-V virtual machines and Remote Desktop sessions through the use of the remote computer's graphics card. Hyper-V virtual machines can now allocate memory when needed instead of allocating a fixed amount through the use of the new Dynamic Memory functionality. Failover Clustering scenarios are now able to utilize drives that are shared across different clusters. DirectAccess support has also been improved with the introduction of support for the 6to4 and ISATAP transition mechanisms.

The ability to utilize Managed Service Accounts in a secure branch office scenario, along with the ability to increase the total amount of active logon sessions for domain controllers, has also been implemented. Support for additional identification types in RRAS and IPsec has also been improved, and the "Restore previous folders at logon" functionality has been updated to preserve the window positions of any previously-opened Windows Explorer window (if applicable).

All bugfixes up through November 2010 have been included with the release of Service Pack 1.