Windows Home Server 2011, code named Vail, is a home server operating system by Microsoft designed for small office/home offices and homes with multiple connected PCs to offer protected file storage, file sharing, automated PC backup, remote access, and remote control of PC desktops. It was released on 6 April 2011 following the release of Power Pack 3 for its aging predecessor, Windows Home Server. Windows Home Server 2011 is the last Windows Home Server release and was succeeded by Windows Server 2012 Essentials.
Compared to its predecessor which worked on the older IA-32 (32-bit) architecture, Windows Home Server 2011 represented new core features not found in its predecessor, as it requires an x86-64 CPU (64-bit), and is often called the "home server" edition of Windows Server 2008 R2 (itself based on the same kernel as the client-oriented Windows 7, which in turn is a heavily improved evolution of Windows Vista). Coupled with fundamental changes in the structure of the client backups and the shared folders, there is no clear method for migrating from the previous version to Windows Home Server 2011.