A Core install of Windows Server 2008 has no Explorer or MMC, but it's not character mode either
Everyone that is experimenting with Windows Server 2008 is excited about the Server Core installation, which is a minimal install of the Server that can run specific roles (like DNS, Active Directory or File Server) with a much smaller footprint and attack surface. A Core install is indeed much smaller than a Full install both in memory and on disk. In fact, if you install both versions using Virtual PC, the difference in size between the two resulting VHD files is quite dramatic. Using the Windows Server 2008 Enterprise Beta 3 my VHD size was about 5.9 GB for a Full and only 1.6 GB for the Core install. Using the Windows Server 2008 June CTP release (also known as IDS3) the VHD size for the Full was around 4.5 GB and the Core was under 1.4 GB.
However, I see that some people expect to find a character-mode only interface and that’s just not the case. It is true that you get a command prompt after you log on and there’s no explorer.exe or iexplore.exe on the hard drive. However, it is still a graphical environment and you do get a logon screen that looks exactly the same as the Full install of Windows Server 2008. In fact, that command prompt appears to you in a window, and you can open multiple command windows at the same time by using “start /w cmd”. Looks like a GUI to me...
In addition to that, you can still do familiar things like press CTRL-ALT-DEL and open Task Manager. Having Task Manager there is very useful for looking at system and process information. It’s also quite handy to start a “New Task…” if you accidentally closed the last command window. You can even start non-command-line tools from the command prompt or Task Manager, like notepad.exe, msinfo32.exe, regedit.exe or control.exe (like in “control timedate.cpl”).
The fact that you can still run these kinds of graphical applications is very important and I’m sure it will help with many application compatibility issues. I was surprised, for instance, that I could run the Virtual PC extensions on Server Core. The install won’t auto-run after you mount the ISO, since this is something that comes from Windows Explorer. However, all you have to do is use the command prompt to go to the D: drive, change to the Windows folder of the CD and run the installer. That’s actually an MSI file, by the way.
There are a few important things that are not in Server Core and are not available even as an optional installable feature, including the .NET Framework and the Microsoft Management Console (MMC). This is the main reason why certain tools like ServerManagerCmd, PowerShell, and ASP.NET are not available in Server Core. The teams are working hard to have even more options available in Core and this will likely lead to a single, completely componentized version of Windows Server in the future. A lot of the work has to do with isolating dependencies and making sure that the Core is as small as possible and the rest is offered as features (some grouped by role) that can be loaded only if needed.
Keep in mind, if you are not a big fan of command lines, that you can manage your Core install using an MMC running on another server running a Full install. For instance, after a Core install with the DNS Server role loaded, you can choose to manage it locally by using the dnscmd.exe command-line tool (to create your DNS zones, for instance) or you can fire the DNS Management MMC from another server. In the same way, you can use the sc.exe command to start/stop the service, or you can use the Services MMC remotely.
Windows Server 2008 is not yet released, so don’t assume that whatever features, roles and tools you see in the current Beta 3 will make it exactly like that into the final product. For instance, although IIS was not available in the Beta 3 as a Core role, the June CTP release now offers that option (although without support for ASP.NET). I encourage you to download the Windows Server 2008 Beta 3 and try Server Core for yourself.
Now for a final little tip. If you're really set on running in character-mode, there's actually a way to do it. Just go to the properties of the command window (by right-clicking the little "C:" icon on the upper left corner of the command windows), and select the "Full Screen" option. The system will actually remember that preference and throw you straight into character mode after logon. Going character-mode is really not what Server Core is about, but you can get that as well. In fact, you can do that full-screen-character-mode command prompt in a Full install of Windows Server 2008 and even in Windows Server 2003. Just remember that If you get stuck on a command that's taking too long in full screen, you can always press Ctrl-Alt-Del and use Task Manager to open another command prompt...
For more on Server Core on this blog, check http://blogs.technet.com/josebda/archive/tags/Server+Core/default.aspx