Server Core is a new Windows installation option introduced in Windows Server 2008.

The original Windows Server 2008 Server Core did not include .NET -- and that limited the things you could use it for.  In Windows Server 2008 R2, Server Core includes .Net 2.0 and .Net v3.5 (neither are installed by default), which opens a new set of possibilities only available in full Server installs until now.  Server Core can now run a wide variety of managed applications, including hosting  ASP.NET, WCF, WF, Windows Services and Console Applications.

An important part of the original Server Core vision is to keep the installation small and focused, minimizing servicing, install time, size, etc. When we added .NET to Server Core, we maintained that vision, putting in only the parts most likely to be needed.  For instance, we've left out the graphics interface (WPF and Windows Forms), design time assemblies, and some tools etc.   We've also included only the 64 bit version of the Framework and tools by default.

When writing .NET applications for Server Core, you can use most – but not all – of the functionality in .NET 2.0 or 3.5 (depending on which you have installed).  If, on your development machine, you use some functionality that is not present in the Server Core version of .NET, your program will probably start to run – but then give hard to diagnose errors when it hits the functionality that is not included.

Those errors can be hard to diagnose, particularly since the code will run fine on a developer machine, with full .NET.  To make it easier to check for these kinds of errors, FxCop can come to the rescue, especially if you use VS 2005 or VS 2008.  FxCop is a standalone application that can be downloaded from http://www.microsoft.com/downloads and is used to analyze managed code assemblies.  It reports issues concerning violations of the Microsoft framework design guidelines for writing robust and easily maintainable code using .NET.  For Server Core, we’ve provided a set of FxCop rules that you can use to validate your applications before you deploy them.  For example, imagine that you have a Windows Service application that uses the System.Media namespace to emit a particular sound when an event happens:  on a full server, with full .NET, this works just fine;  on Server Core, it will fail.  In this case, by loading the Server Core FxCop rules and scanning your code, you will find all the dangerous places where your application may break.  We highly recommend using these rules before deploying your application to a Server Core box. 

Like every other rule, this one can be loaded into FXCOP by using the “Project” menu and selecting “Add Rules…” option.  To check if the action succeeded, you can see it in the rules tab.  Once loaded, these rules will scan all the assemblies in your FxCop project, looking for illegal usage of non-supported Framework type.

If you wish to download the FxCop Server Core validation rule, it can be found in this post.  Also, be advised that these rules were only tested against FXCOP version 1.36.

For a complete list of supported namespaces, please, refer to Server Core’s documentation.

References:

The Server Core step by step guide is at:

·         Read online: http://technet.microsoft.com/en-us/library/cc753802.aspx

·         Download as a Word doc: http://www.microsoft.com/downloads/details.aspx?familyid=B16F4DC4-A3D3-4DC7-AA51-A1C6728B217A&displaylang=en

The namespace list is at: http://blogs.technet.com/server_core/archive/2008/11/25/net-2-0-and-server-core-in-windows-server-2008-r2.aspx and once the WS08 R2 SDK is published it will be include there as well.

Those of you that installed the beta build may have noticed that we made WoW64 an optional feature in Server Core for R2. In the beta it was not installed by default, which caused its share of headaches due to many installers still being 32bit or using 32bit custom actions. Based on all the feedback we received from the beta, in the RC build WoW64 is now installed by default so 32bit tools and installers will work out of the box. WoW64 is still optional, so can be uninstalled if desired.

The following server roles and features have WoW64 packages so if you need 32bit support when using any of these you will need to install the server role or feature and then the WoW64 package:

A slight detour from the Windows Server 2008 R2 posts this time around to cover a topic that has been coming up recently: UAC on Server Core.

UAC is not available in Server Core, since it is a command line only interface, doesn’t have IE, or support for user applications. In addition, to use UAC with the command prompt you need to have the Explorer Shell so that you can click Start, right click on Command Prompt, and select run as administrator, which obviously isn’t possible on Server Core.

To disable UAC on Server Core you can use reg.exe or regedit.exe to set the EnableLUA value under the following Registry path to 0 and reboot:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System

More on Windows Server 2008 R2 next time.

This time I’ll cover what I meant last time by a subset of .NET 2.0, with future posts covering the other additions in more detail. Not everything required for full .NET 2.0 support is included in Server Core. Instead of increasing the Server Core footprint to add functionality that isn’t “core” to Server Core (couldn’t resist), we added the portions of .NET 2.0 that align with what is already in Server Core. Therefore, the following namespaces are not available as part of .NET 2.0 on Server Core:

·         Microsoft.Aspnet.Snapin

·         Microsoft.Ink

·         Microsoft.ManagementConsole.*

·         Microsoft.StylusInput.*

·         Microsoft.VisualBasic.Compatibility.VB6

·         Microsoft.Windows.Themes

·         Microsoft.WindowsCE.Forms

·         Microsoft.WindowsMobile.DirectX.*

·         System.ComponentModel.Design.*

·         System.Data.Design

·         System.Deployment.Application

·         System.Diagnostics.Design

·         System.Media

·         System.Messaging.*

·         System.Speech.*

·         System.Web.UI.Design.* (design time support in this namespace is unavailable, runtime support for expression builders is supported)

·         System.Windows.*

·         UIAutomationClientsideProviders

As you can see from the list, these require functionality not available in Server Core, e.g. DirectX, UI/MMC, Multimedia, Tablet support, etc.

To install .NET 2.0 on Server Core you can run:

·         Start /w ocsetup  NetFx2-ServerCore

If 32bit support is needed you first need to install WoW64 and then .NET 2.0 WoW64 support, the following assume the above command has already been run:

·         Start /w ocsetup ServerCore-WOW64

·         Start /w ocsetup NetFx2-ServerCore-WOW64

In the Server Core installation option, there is a way to remove the server roles and optional features from the disk, to free up more space. In addition to reducing disk usage, this could be used to ensure an administrator doesn’t add a role or feature to a server that is supposed to perform a fixed function.

Warning: This is a one way operation, once you remove a role or feature there is NO way to bring it back. If you realize later that you need the role or feature the only option is to reinstall.

To do this:

1.       Run: pkgmgr /up:<package to remove>

2.       Reboot – you can remove multiple packages before rebooting.

3.       Wait about 30 minutes for the disk cleanup to occur.

You will then see the disk space used by the role or feature is freed up, oclist will no longer show the role or feature as being available, and trying to install it using ocsetup will result in an error. Once again, read the warning above – there is no way to put the role or feature back, it is permanently gone from the system.

The role and feature packages available for removal are:

·         Microsoft-Hyper-V-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-BLB-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-DFSN-ServerCore~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-DFSR-ServerEdition-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-DhcpServerCore-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-DirectoryServices-ADAM-SrvFnd-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-DirectoryServices-DomainController-SrvFnd-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-DNS-Server-Core-Role-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-FailoverCluster-Core-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-FileReplication-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-IIS-WebServer-Core-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-Internet-Naming-Service-SC-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-MultipathIo-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-NetworkLoadBalancingHeadlessServer-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-NFS-ServerFoundation-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-Printing-ServerCore-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-QWAVE-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-RemovableStorageManagementCore-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-SecureStartup-OC-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-SNMP-SC-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-SUA-Core-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-Telnet-Client-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

If you are running on an x86 box, change the amd64 above to x86.

In addition to the roles and features listed in oclist, it is also possible to remove IME support as well as the supporting fonts by removing the following packages:

·         Microsoft-Windows-ServerCore-EA-IME-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

·         Microsoft-Windows-ServerCore-EA-Fonts-Package~31bf3856ad364e35~amd64~~6.0.6001.18000

Removing these will reduce the on disk footprint by ~200MB.

Andrew

p.s. - don't forget about the warning above

A couple of quick tips this time around.

If you want to determine if you are running on Server Core from a script, you can do this via WMI. The command line way is:

wmic path win32_operatingsystem get OperatingSystemSKU /value

The value can then be converted to hex and mapped to the list at: http://msdn2.microsoft.com/en-us/library/ms724358.aspx

Here is a tip I received from the HP Windows Server Academy team. If you don’t want to include all of the many IIS options in the output of Oclist, run:

Oclist | find “Installed” | find /v “IIS”

Note that the other methods of remote management are either enabled out of the box, such as WMI, or when enabled the firewall is configured to allow them, such as Terminal Server remote administration mode.