Windows Server 2012
Windows Server 2012 is the fifth version of the Windows Server operating system by Microsoft, as part of the Windows NT family of operating systems. It is the server version of Windows based on Windows 8 and succeeds Windows Server 2008 R2, which is derived from the Windows 7 codebase, released nearly three years earlier. Two pre-release versions, a developer preview and a beta version, were released during development. The software was officially launched on September 4, 2012, two months before the release of Windows 8. A successor was released on October 18, 2013, entitled Windows Server 2012 R2. Microsoft ended mainstream support for Windows Server 2012 on October 9, 2018, and extended support will end on October 10, 2023.

Unlike its predecessor, Windows Server 2012 has no support for Itanium-based computers, and has four editions. Various features were added or improved over Windows Server 2008 R2 (with many placing an emphasis on cloud computing), such as an updated version of Hyper-V, an IP address management role, a new version of Windows Task Manager, and ReFS, a new file system. Windows Server 2012 received generally good reviews in spite of having included the same controversial Metro-based user interface seen in Windows 8, which includes the Charms Bar for quick access to settings in the desktop environment.

History
Windows Server 2012, codenamed "Windows Server 8", is the fifth release of Windows Server family of operating systems developed concurrently with Windows 8. It was not until April 17, 2012 that the company announced that the final product name would be "Windows Server 2012".

Microsoft introduced Windows Server 2012 and its developer preview in the BUILD 2011 conference on September 9, 2011. However, unlike Windows 8, the developer preview of Windows Server 2012 was only made available to MSDN subscribers. It included a graphical user interface (GUI) based on Metro design language and a new Server Manager, a graphical application used for server management. On February 16, 2012, Microsoft released an update for developer preview build that extended its expiry date from April 8, 2012 to January 15, 2013.

Before Windows Server 2012 was finalized, two test builds were made public. A public beta version of Windows Server 2012 was released along with the Windows 8 Consumer Preview on February 29, 2012. The release candidate of Windows Server 2012 was released on May 31, 2012, along with the Windows 8 Release Preview.

The product was released to manufacturing on August 1, 2012 (along with Windows 8) and became generally available on September 4, that year. However, not all editions of Windows Server 2012 were released at the same time. Windows Server 2012 Essentials was released to manufacturing on October 9, 2012 and was made generally available on November 1, 2012. As of September 23, 2012, all students subscribed to DreamSpark program can download Windows Server 2012 Standard or Datacenter free of charge.

Windows Server 2012 is based on Windows Server 2008 R2 and Windows 8 and requires x86-64 CPUs (64-bit), while Windows Server 2008 worked on the older IA-32 (32-bit) architecture as well. 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 Server 2012.

Features

Installation options
Unlike its predecessor, Windows Server 2012 can switch between "Server Core" and "Server with a GUI" installation options without a full reinstallation. Server Core – an option with a command-line interface only – is now the recommended configuration. There is also a third installation option that allows some GUI elements such as MMC and Server Manager to run, but without the normal desktop, shell or default programs like File Explorer.

User interface
Server Manager has been redesigned with an emphasis on easing management of multiple servers. The operating system, like Windows 8, uses the Metro-based user interface unless installed in Server Core mode. Windows Store is available in this version of Windows but is not installed by default. Windows PowerShell in this version has over 2300 commandlets, compared to around 200 in Windows Server 2008 R2.

Task Manager

Windows Server 2012 includes a new version of Windows Task Manager together with the old version. In the new version the tabs are hidden by default, showing applications only. In the new Processes tab, the processes are displayed in varying shades of yellow, with darker shades representing heavier resource use. Information found in the older versions are now moved to the new Details tab. The Performance tab shows "CPU", "Memory", "Disk", "Wi-Fi" and "Ethernet" graphs. Unlike the Windows 8 version of Task Manager (which looks similar), the "Disk" activity graph is not enabled by default. The CPU tab no longer displays individual graphs for every logical processor on the system by default, although that remains an option. Additionally, it can display data for each non-uniform memory access (NUMA) node. When displaying data for each logical processor for machines with more than 64 logical processors, the CPU tab now displays simple utilization percentages on heat-mapping tiles. The color used for these heat maps is blue, with darker shades again indicating heavier utilization. Hovering the cursor over any logical processor's data now shows the NUMA node of that processor and its ID, if applicable. Additionally, a new Startup tab has been added that lists startup applications, however this tab does not exist in Windows Server 2012. The new task manager recognizes when a Windows Store app has the "Suspended" status.

IP address management (IPAM)
Windows Server 2012 has an IP address management role for discovering, monitoring, auditing, and managing the IP address space used on a corporate network. The IPAM is used for the management and monitoring of Domain Name System (DNS) and Dynamic Host Configuration Protocol (DHCP) servers. Both IPv4 and IPv6 are fully supported.

Active Directory
Windows Server 2012 has a number of changes to Active Directory from the version shipped with Windows Server 2008 R2. The Active Directory Domain Services installation wizard has been replaced by a new section in Server Manager, and a GUI has been added to the Active Directory Recycle Bin. Multiple password policies can be set in the same domain. Active Directory in Windows Server 2012 is now aware of any changes resulting from virtualization, and virtualized domain controllers can be safely cloned. Upgrades of the domain functional level to Windows Server 2012 are simplified; it can be performed entirely in Server Manager. Active Directory Federation Services is no longer required to be downloaded when installed as a role, and claims which can be used by the Active Directory Federation Services have been introduced into the Kerberos token. Windows Powershell commands used by Active Directory Administrative Center can be viewed in a "Powershell History Viewer".

Hyper-V
Windows Server 2012, along with Windows 8, includes a new version of Hyper-V, as presented at the Microsoft BUILD event. Many new features have been added to Hyper-V, including network virtualization, multi-tenancy, storage resource pools, cross-premises connectivity, and cloud backup. Additionally, many of the former restrictions on resource consumption have been greatly lifted. Each virtual machine in this version of Hyper-V can access up to 64 virtual processors, up to 1 terabyte of memory, and up to 64 terabytes of virtual disk space per virtual hard disk (using a new  format). Up to 1024 virtual machines can be active per host, and up to 8000 can be active per failover cluster. SLAT is a required processor feature for Hyper-V on Windows 8, while for Windows Server 2012 it is only required for the supplementary RemoteFX role.

ReFS

Resilient File System (ReFS), codenamed "Protogon", is a new file system in Windows Server 2012 initially intended for file servers that improves on NTFS in some respects. Major new features of ReFS include:

Improved reliability for on-disk structures ReFS uses B+ trees for all on-disk structures including metadata and file data. Metadata and file data are organized into tables similar to a relational database. The file size, number of files in a folder, total volume size and number of folders in a volume are limited by 64-bit numbers; as a result ReFS supports a maximum file size of 16 exabytes, a maximum of 18.4 × 1018 folders and a maximum volume size of 1 yottabyte (with 64 KB clusters) which allows large scalability with no practical limits on file and folder size (hardware restrictions still apply). Free space is counted by a hierarchical allocator which includes three separate tables for large, medium, and small chunks. File names and file paths are each limited to a 32 KB Unicode text string.
Built-in resilience ReFS employs an allocation-on-write update strategy for metadata,  which allocates new chunks for every update transaction and uses large IO batches. All ReFS metadata has built-in 64-bit checksums which are stored independently. The file data can have an optional checksum in a separate "integrity stream", in which case the file update strategy also implements allocation-on-write; this is controlled by a new "integrity" attribute applicable to both files and directories. If nevertheless file data or metadata becomes corrupt, the file can be deleted without taking the whole volume offline. As a result of built-in resiliency, administrators do not need to periodically run error-checking tools such as CHKDSK when using ReFS.
Compatibility with existing APIs and technologies ReFS does not require new system APIs and most file system filters continue to work with ReFS volumes.  ReFS supports many existing Windows and NTFS features such as BitLocker encryption, Access Control Lists, USN Journal, change notifications, symbolic links, junction points, mount points, reparse points, volume snapshots, file IDs, and oplock. ReFS seamlessly integrates with Storage Spaces, a storage virtualization layer that allows data mirroring and striping, as well as sharing storage pools between machines. ReFS resiliency features enhance the mirroring feature provided by Storage Spaces and can detect whether any mirrored copies of files become corrupt using background data scrubbing process, which periodically reads all mirror copies and verifies their checksums then replaces bad copies with good ones.

Some NTFS features are not supported in ReFS, including object IDs, short names, file compression, file level encryption (EFS), user data transactions, hard links, extended attributes, and disk quotas. Sparse files are supported. Support for named streams is not implemented in Windows 8 and Windows Server 2012, though it was later added in Windows 8.1 and Windows Server 2012 R2. ReFS does not itself offer data deduplication. Dynamic disks with mirrored or striped volumes are replaced with mirrored or striped storage pools provided by Storage Spaces. In Windows Server 2012, automated error-correction with integrity streams is only supported on mirrored spaces; automatic recovery on parity spaces was added in Windows 8.1 and Windows Server 2012 R2. Booting from ReFS is not supported either.

IIS 8.0
Windows Server 2012 includes version 8.0 of Internet Information Services (IIS). The new version contains new features such as SNI, CPU usage caps for particular websites, centralized management of SSL certificates, WebSocket support and improved support for NUMA, but few other substantial changes were made.

Remote Desktop Protocol 8.0
Remote Desktop Protocol has new functions such as Adaptive Graphics (progressive rendering and related techniques), automatic selection of TCP or UDP as transport protocol, multi touch support, DirectX 11 support for vGPU, USB redirection supported independently of vGPU support, etc. A "connection quality" button is displayed in the RDP client connection bar for RDP 8.0 connections; clicking on it provides further information about connection, including whether UDP is in use or not.

Scalability
Windows Server 2012 supports the following maximum hardware specifications. Windows Server 2012 improves over its predecessor Windows Server 2008 R2:

System requirements

Windows Server 2012 does not support Itanium and runs only on x64 processors.

Upgrades from Windows Server 2008 and Windows Server 2008 R2 are supported, although upgrades from prior releases are not.

Editions
Windows Server 2012 has four editions: Foundation, Essentials, Standard  and Datacenter.

Reception
Reviews of Windows Server 2012 have been generally positive. Simon Bisson of ZDNet described it as "ready for the datacenter, today," while Tim Anderson of The Register said that "The move towards greater modularity, stronger automation and improved virtualisation makes perfect sense in a world of public and private clouds" but remarked that "That said, the capability of Windows to deliver obscure and time-consuming errors is unchanged" and concluded that "Nevertheless, this is a strong upgrade overall."

InfoWorld noted that Server 2012's use of Windows 8's panned "Metro" user interface was countered by Microsoft's increasing emphasis on the Server Core mode, which had been "fleshed out with new depth and ease-of-use features" and increased use of the "practically mandatory" PowerShell. However, Michael Otey of Windows IT Pro expressed dislike with the new Metro interface and the lack of ability to use the older desktop interface alone, saying that most users of Windows Server manage their servers using the graphical user interface rather than PowerShell.

Paul Ferrill wrote that "Windows Server 2012 Essentials provides all the pieces necessary to provide centralized file storage, client backups, and remote access," but Tim Anderson contended that "Many businesses that are using SBS2011 and earlier will want to stick with what they have", citing the absence of Exchange, the lack of ability to synchronize with Active Directory Federation Services and the 25-user limit, while Paul Thurott wrote "you should choose Foundation only if you have at least some in-company IT staff and/or are comfortable outsourcing management to a Microsoft partner or solution provider" and "Essentials is, in my mind, ideal for any modern startup of just a few people."

Windows Server 2012 R2
A second release, Windows Server 2012 R2, which is derived from the Windows 8.1 codebase, was released to manufacturing on August 27, 2013 and became generally available on October 18, 2013, by Microsoft. A service pack, formally designated Windows Server 2012 R2 Update, was released in April 2014.

See also
 Comparison of Microsoft Windows versions
 Comparison of operating systems
 History of Microsoft Windows
 List of operating systems
 Microsoft Servers

Notes

Extended Security Updates
Microsoft Announced in July 2021 they will distribute Extended Security Updates for SQL Server 2012, Windows Server 2012, and Windows Server 2012 R2, for a maximum of three years after the end of Extended Support date.

End of Support
Microsoft originally planned to end support for Windows Server 2012 and Windows Server 2012 R2 on January 10, 2023, but in order to provide customers the standard transition lifecycle timeline, Microsoft extended Windows Server 2012 and 2012 R2 support in March 2017 by 9 months. With a final set end date, Windows Server 2012 will end Extended Support on October 10, 2023.

References

Further reading

External links

 
 Windows Server 2012 R2 and Windows Server 2012 on TechNet
 Windows Server 2012 R2 on MSDN
 Windows Server 2012 on MSDN
 Tutorials and Lab Manual Articles of Windows Server 2012 R2 

Windows Server
X86-64 operating systems
2012 software