Understanding Windows Server Core

Windows server core is a “minimal” installation option for Windows Server 2008. What this means is that when you choose this option during setup (or when using unattended setup), Windows Server 2008 installs a minimum set of components on your machine that will allow you to run certain (but not all) server roles. In other words, selecting the Windows server core installation option installs only a subset of the binaries that are installed when you choose the full installation option for Windows Server 2008.

Here are some of the Windows Server 2008 components that are not installed when you specify the Windows server core installation option during setup:

• No desktop shell (which means no glass, wallpaper, or screen savers either)

• No Windows Explorer or My Computer (we already said no desktop shell, right?)

• No .NET Framework or CLR (which means no support for managed code, which also means no PowerShell support)

• No MMC console or snap-ins (so no Administrative tools on the Start menu-whoops! I forgot, no Start menu!)

• No Control Panel applets (with a few small exceptions)

• No Internet Explorer or Windows Mail or WordPad or Paint or Search window (no Windows Explorer!) or GUI Help and Support or even a Run box.

Wow, that sounds like a lot of stuff that’s missing in a Windows server core installation of Windows Server 2008! Actually though, it’s not-compare the preceding list to the following list of components that are available on a Windows server core server.

First, you’ve still got the kernel. You always need the kernel.

Then you’ve got hardware support components such as the Hardware Abstraction Layer (HAL) and device drivers. But it’s only a limited set of device drivers that supports disks, network cards, basic video support, and some other stuff. A lot of in-box drivers have been removed from the Windows server core installation option, however-though there is a way to install out-of-box drivers if you need to.

Next, you’ve still got all the core subsystems that are needed by Windows Server 2008 in order to function. That means you’ve got the security subsystem and Winlogon, the networking subsystem, the file system, RPC and DCOM, SNMP support, and so on. Without these subsystems, your server simply wouldn’t be able to do anything at all, so they’re a necessity for a Windows server core installation.

Then you’ve got various components you need to configure different aspects of your server. For example, you have components that let you create user accounts and change passwords, enable DHCP or assign a static IP address, rename your server or join a domain, configure Windows Firewall, enable Automatic Updates, choose a keyboard layout, set the time and date, enable Remote Desktop, and so on. Many of these configuration tasks can be performed using various command-line tools included in a Windows server core installation (more about tools in a moment), but a few of them use scripts or expose minimal UI.

There are some additional infrastructure components present as well on a Windows server core installation. For instance, you still have the event logs plus a command-line tool for viewing, configuring, and forwarding them using Windows eventing. You’ve got performance counters and a command-line tool for collecting performance information about your server. You have the Licensing service, so you can activate and use your server as a fully licensed machine. You’ve got IPSec support, so your server can securely communicate on the network. You’ve got NAP client support, so your server can participate in a NAP deployment. And you’ve got support for Group Policy of course.

Then there are various tools and infrastructure items to enable you to manage your Windows server core server. You’ve got the command prompt cmd.exe, so you can log on locally to your server and run various commands from a command-prompt window. In fact, as we saw, a command-prompt window is already open for you when you first log on to a Windows server core server. What happens, though, if you accidentally close this window? Fortunately, a Windows server core installation still includes Task Manager, so if you close your command window you can start another by doing the following:

1. Press CTRL+SHIFT+ESC, to open Task Manager.

2. On the Applications tab, click New Task.

3. Type cmd and click OK.

In addition to the command prompt, of course, there are dozens (probably over a hundred, and more when different roles and features are installed) of different command-line tools available on Windows Server 2008 for both full and server core installation options. What I’m talking about is Arp, Assoc, At, Attrib, BCDEdit Cacls, Certutil, Chdir, chkdsk, Cls, Copy, CScript, Defrag, Dir, and so on. A lot of the commands listed in the “Windows Command-Line Reference A–Z,” found on Microsoft TechNet, are available on a Windows server core server- not all, mind you, but a lot of them.

You can also enable Remote Desktop on a Windows server core installation, and this lets you connect to it from another machine using Remote Desktop Connection (RDC) and start a Terminal Services session running on it. Once you’ve established your session, you can use the command prompt to run various commands on your server, and you can even use the new Remote Programs feature of RDC 6.0 to run a remote command prompt on a Windows server core server from an administrative workstation running Windows Vista.

There’s also a WMI infrastructure on your Windows server core server that includes many of the usual WMI providers. This means you can manage your Windows server core server either by running WMI scripts on the local machine from the command prompt or by scheduling their operation using schtasks.exe. (There’s no Task Schedule UI available, however.) Or you can manage your server remotely by running remote WMI scripts against it from another machine. And having WMI on a Windows server core server means that remote UI tools such as MMC snap-ins running on other systems (typically, either a full installation of Windows Server 2008 or an administrator workstation running Windows Vista with Remote Server Administration Tools installed) can connect to and remotely administer your Windows server core server. Plus there’s also a WS-Management infrastructure on a Windows server core installation. WS-Management is a new remote-management infrastructure included in Windows Vista and Windows Server 2008, and involves Windows Remote Management (WinRM) on the machine being managed and the Windows Remote Shell (WinRM) for remote command execution from the machine doing the managing.

Then there are various server roles and optional features you can install on a Windows server core server so that the machine can actually do something useful on your network, like be a DHCP server or a domain controller or print server. Then there are a few necessary GUI tools that actually are present on a Windows server core server. For example, we already saw that the command prompt (cmd.exe) is available, and so is Task Manager. Another useful tool on a Windows server core server is Regedit.exe, which can be launched either from the command line or from Task Manager. Next is Notepad. During the early stages of developing and testing Windows Server 2008, one of the most common requests from participants in the Microsoft Technology Adoption Program (TAP) for Windows Server 2008 was this: We need a tool on Windows server core servers that we can use to view logs, edit scripts, and perform other essential administrative tasks.

Who ever expected that the lowly and oft-maligned Notepad would be so important to administrators who work in enterprise environments? Anyway, before we move on and talk a bit about the rationale behind why Microsoft decided to offer the Windows server core installation option in Windows Server 2008, let’s hear from one of our experts about how the Windows server core product team managed to make this thing work. After all, Windows components have a lot of dependencies with one another and especially with the desktop shell and Internet Explorer, so it will be interesting to hear how they took so many components out of this installation option for the product without causing it to break.

Source of Information : Introducing Windows Server 2008

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