Microsoft designed Windows Server 2008 and Windows Server 2008 R2 so that they can either be deployed in the usual way or in a server core configuration. A server core deployment is a minimal Windows Server deployment in which only the most critical Windows components are installed. The operating system even lacks a true GUI interface. When is it best to use a server core deployment or when it is better to use a traditional full installation?
Server core deployments: not for everyone
Remember the old adage: Just because you can do something doesn’t necessarily mean you should. Server core deployments are more difficult to manage than traditional Windows Server deployments. While it is true that you can perform the majority of the management tasks remotely using GUI tools, there will be times when you will have no choice but to manage a core server from the command prompt. If command-line-based management makes you uncomfortable, then you might be better off using a full Windows Server installation rather than a server core installation.
Limitations and compatibility
As I mentioned earlier, server core deployments lack many of the components found in traditional Windows Server deployments. While this minimalist approach does have its advantages, it also limits what you can do with server core. Don’t expect to use server core as an application server. Few enterprise class applications will run on server core deployments (although I expect this to change in the future). Instead, server core is better suited for use with infrastructure servers. In fact, only certain Windows Server roles can be deployed on server core and most of those roles are infrastructure components.
The actual roles that can be deployed on server core vary depending on whether you are running Windows Server 2008 or Windows Server 2008 R2. Here is a list of the compatible roles, along with some noteworthy limitations:
- Active Directory
- Active Directory Certificate Services (Windows Server 2008 R2 only)
- Active Directory Lightweight Directory Services
- BranchCache Hosted Cache (Windows Server 2008 R2 Enterprise and Datacenter Editions Only)
- DHCP Server
- DNS Server
- File Services (limited to a single standalone DFS Root in Standard Edition)
- Print Services
- Streaming Media Services
- Web Server (IIS)
Benefits and uses
Although you can run the roles listed above on server core, you can also run those same roles on a full-blown Windows Server installation. So why would you ever want to use server core? There are two main reasons:
- Security. Server core deployments have a much smaller attach surface than traditional Windows Server deployments and many of the components that are often targeted by hackers do not even exist on core servers.
Even if your organization isn’t the textbook high-security environment, you might still be able to benefit from the security offered by server core. Two of the most critical roles on a Windows Server network are the Active Directory role and the Active Directory Certificate Services role. If someone manages to compromise your domain controllers, or your certificate authority, then they basically own your network. It may be a good idea to host these two roles on core servers.
- Server virtualization. Because server virtualization involves sharing hardware resources among multiple virtual servers, making efficient use of hardware resources is critical. After all, the more virtual servers you can cram onto a physical server, the better the return on your hardware investment.
Server core is ideal for use in virtual data centers because of its small footprint. Server core virtual machines require very little disk space, and they typically consume far less memory and CPU resources than a traditional Windows Server deployment. The hardware resources that you save by using server core virtual machines can be allocated to other virtual machines that require greater hardware resources.
There are advantages to using server core deployments, especially when it comes to security or to conserving hardware resources. Even so, administrators must consider whether they are willing to climb the learning curve as well as the additional management responsibilities that come with this approach.
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ABOUT THE AUTHOR
Brien M. Posey, MCSE, has previously received Microsoft's MVP award for Exchange Server, Windows Server and Internet Information Server (IIS). Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. You can visit Brien's personal website at www.brienposey.com.