Many enterprise networks today use servers that are dedicated to a particular role. When a server is performing a single role, it does not make sense to have so many other processes running on the server that contribute little or nothing to that role. Windows Server 2012 R2 provides installation options that enable administrators to keep the unnecessary resources installed on a server to a minimum.
Using Server Core
Windows Server 2012 R2 includes an installation option that minimizes the user interface on a server. When you select the Windows Server Core installation option, you will install a stripped-down version of the operating system. There is no Start menu, no desktop Explorer shell, no Microsoft Management Console (MMC), and virtually no graphical applications. All you see when you start the computer is a single window with a command prompt, as shown in Figure 1-1.
FIGURE 1-1 The default Server Core interface
NOTE: WHAT IS SERVER CORE?
Server Core is not a separate product or edition. It is an installation option included with the Windows Server 2012 R2 Standard edition and the Windows Server 2012 R2 Datacenter edition.
There are several advantages to running servers using Server Core:
– Hardware resource conservation Server Core eliminates some of the most memory-intensive and processor-intensive elements of the Windows Server 2012 R2 operating system, thus devoting more of the system hardware to running essential services.
– Reduced disk space Server Core requires less disk space for the installed operating system elements and less swap space, which maximizes the utilization of the server’s storage resources.
– Reduced patch frequency The graphical elements of Windows Server 2012 R2 are among the most frequently updated, so running Server Core reduces the number of updates that administrators must apply. Fewer updates also mean fewer server restarts and less downtime.
– Reduced attack surface The less software there is running on the computer, the fewer entrance points for attackers to exploit. Server Core reduces the potential openings presented by the operating system, increasing its overall security.
When Microsoft first introduced the Server Core installation option in Windows Server 2008, it was an intriguing idea, but few administrators took advantage of it. The main reason for this was that most server administrators were not sufficiently conversant with the command-line interface that is used to manage a Windows server without a GUI.
In Windows Server 2008 and Windows Server 2008 R2, the decision to install the operating system using the Server Core option was irrevocable. Once you installed the operating system using Server Core, there was no way to get the GUI back except to perform a complete reinstallation. That has all changed in Windows Server 2012 and Windows Server 2012 R2.
You can now switch a server from the Server Core option to the Server with a GUI option and back again, at will, by using Windows PowerShell commands.
Note: THERE AND BACK AGAIN
For more information on converting from the Server Core option to the Server with a GUI option and back again, see “Objective 1.2: Configure servers,” later in coming sections.
This ability means that administrators can install Windows Server 2012 R2 using the Server with a GUI option, configure the server using the familiar graphical tools, and then switch the server to Server Core to take advantage of the benefits listed earlier.
SERVER CORE DEFAULTS
In Windows Server 2012 R2, Server Core is the default installation option for reasons other than simply providing administrators with the ability to switch options after installing. In Windows Server 2012 R2, Microsoft is attempting to fundamentally modify the way that administrators work with their servers. Server Core is now the default installation option because in the new way of managing servers, administrators should rarely, if ever, have to work at the server console, either physically or remotely.
Windows Server has long been capable of remote administration, but this capability has been piecemeal. Some Microsoft Management Console (MMC) snap-ins enabled administrators to connect to remote servers, and Windows PowerShell 2.0 provided some remote capabilities from the command line, but Windows Server 2012 R2, for the first time, includes comprehensive remote administration tools that nearly eliminate the need to work at the server console.
The new Server Manager application in Windows Server 2012 R2 enables administrators to add servers from all over the enterprise and create server groups to facilitate the simultaneous configuration of multiple systems. The new Windows PowerShell 4.0 environment increases the number of available cmdlets from 230 to well over 2,000.
With tools like these, you can install your servers using the Server Core option, execute a few commands to join each server to an Active Directory Domain Services domain, and then never touch the server console again. You can perform all subsequent administration tasks, including the deployment of roles and features, by using Server Manager and Windows PowerShell from a remote workstation.
SERVER CORE CAPABILITIES
In addition to omitting most of the graphical interface, a Server Core installation omits some of the server roles found in a Server with a GUI installation. However, the Server Core option in Windows Server 2012 R2 includes 12 of the 19 roles, plus support for SQL Server 2012, as opposed to only 10 roles in Windows Server 2008 R2 and nine in Windows Server 2008.
Table 1-4 lists the roles and features that are available and not available in a Windows Server 2012 R2 Server Core installation.
TABLE 1-4 Windows Server 2012 R2 Server Core roles
Using the Minimal Server Interface
If the advantages of Server Core sound tempting, but there are traditional server administration tools you don’t want to give up, Windows Server 2012 R2 provides a compromise called the Minimal Server Interface.
The Minimal Server Interface is a setting that removes some of the most hardware-intensive elements from the graphical interface. These elements include Internet Explorer and the components of the Windows shell, including the desktop, File Explorer, and the Windows 8 desktop apps. Also omitted are the Control Panel items implemented as shell extensions, including the following:
– Programs and Features
– Network and Sharing Center
– Devices and Printers Center
– Windows Update
– Storage Spaces
What’s left in the Minimal Server Interface are the Server Manager application, the MMC application, Device Manager, and the entire Windows PowerShell interface. This provides administrators with most of the tools they need to manage local and remote servers.
To configure a Windows Server 2012 R2 Server with a GUI installation to use the Minimal Server Interface, you must remove the Server Graphical Shell feature by using Windows PowerShell or the Remove Roles And Features Wizard, as shown in Figure 1-2.
FIGURE 1-2 Using the User Interfaces And Infrastructure feature in the Remove Roles And Features Wizard
Using Features on Demand
During a Windows Server 2012 R2 installation, the Setup program copies the files for all the operating system components from the installation medium to a directory called WinSxS, the side-by-side component store. This enables you to activate any of the features included with Windows Server 2012 R2 without having to supply an installation medium.
The only drawback of this arrangement is that the WinSxS directory permanently occupies approximately 5 GB of disk space, much of which is, in many cases, devoted to data that will never be used after the initial server deployment.
With the increasing use of VMs to distribute server roles, enterprise networks often have more copies of the server operating system than ever before, and therefore they have more wasted disk space. In addition, the advanced storage technologies often used by today’s server infrastructures, such as storage area networks (SANs) and solid state drives (SSDs), are making that disk space more expensive.
Features on Demand, introduced in Windows Server 2012, is a third state for operating system features that enables administrators to conserve disk space by removing specific features, not only from operation but also from the WinSxS directory.
Features on Demand provides a third installation state for each of the features in Windows Server 2012 R2. In versions of the operating system prior to Windows Server 2012, features could only be Enabled or Disabled. Features on Demand provides the following three states:
– Disabled with payload removed
To implement this third state, you must use the Windows PowerShell Uninstall-Windows-Feature cmdlet, which now supports a new –Remove flag. Thus, the Windows PowerShell command to disable the Server Graphical Shell and remove its source files from the WinSxS directory would be as follows:
Uninstall-WindowsFeature Server-Gui-Shell -Remove
Once you delete the source files for a feature from the WinSxS folder, they are not irretrievable.If you attempt to enable that feature again, the system will download it from Windows Update or, alternatively, retrieve it from an image file you specify by using the
–Source flag with the Install-WindowsFeature cmdlet. This enables you to retrieve the required files from a removable disk or from an image file on the local network. You can also use Group Policy to specify a list of installation sources.
NOTE: FEATURES ON DEMAND
This ability to retrieve source files for a feature from another location is the actual functionality to which the name Features on Demand refers. Microsoft often uses this capability to reduce the size of updates downloaded from the Internet. When the user installs the update, the program downloads the additional files required and completes the installation.
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