Windows Server 2003 Requirements

At this point, we're not ready to address the actual hardware requirements of the servers themselves. (That's covered fully in Chapters 5 and 13.) Instead, we're going to look at operating system requirements and configuration options that will help you make decisions environment design. First, we need to determine which flavor of Windows Server 2003 you will use.

Windows 2003 Server Versions

Right off the bat you'll be confronted with a major decision, namely, which version of Windows Server 2003 to use. Windows Server 2003 comes in 32- and 64-bit versions. 32-bit versions are segmented into Web Server, Standard Server, Enterprise Server, and Datacenter Server.

The Web Server version of Windows Server 2003 does not have the ability to host Terminal Server sessions for applications (although it does allow for that two-user limited remote desktop option). So we can toss the Web Server out of the mix right away.

There are pages and pages of small differences between the other three versions of Windows 2003, but Figure 2.6 highlights those that actually impact Terminal Server environments.

Feature	Standard	Enterprise	Datacenter
Supports Terminal Services	•	•	•
Network Load Balancing Clusters	•	•	•
Can utilize a Session Directory		•	•
Can host a Session Directory	•	•	•
Cluster Services		•	•
Max number of processors	4	8	32
Max memory	4GB	32GB	64GB

Figure 2.6: 32-bit Windows Server 2003 Terminal Server features

In terms of basic Terminal Server functionality, all three versions work in the same way. The version of server you choose will ultimately be decided by your final design and the features you are required to implement.

The two most important differences are the number of processors and the amount of memory that each server supports. The version of Windows Server 2003 that you choose will depend on whether you build many little servers or a few big ones. (This decision is critical, and fully covered in Chapter 5.)

The other important difference is that the Standard Server version can't use Session Directory. If you're planning on using a third-party product such as Citrix MetaFrame, Tarantella New Moon Canaveral iQ, or RES PowerFure, then this might not matter and you can just use Standard Server. However, if you're going for a pure Terminal Server environment and want your users to be able to connect back into disconnected sessions in a multi-server environment, you'll need Session Directory, and thus at least the Enterprise Server version.

If you do plan on using a third-party product, remember that each implements different types of management and load-balancing schemes. Before deciding on a Windows Server version, look at what the product offers and requires so as to avoid wasting extra money on server licenses that are not required.

Probably in 99% of cases, the Session Directory or the processor and memory limitations are the reasons why people choose Enterprise Server over Standard Server. While it's true that Enterprise Server also supports additional functionality such as clustering, this functionality is rarely (if ever) used on the Terminal Servers themselves, since user sessions (unlike standard services or server applications) cannot be clustered.

Server Hardware Recommendations

In addition to the underlying operating system, there are certain server hardware requirements that your Terminal Servers will have to meet in order to perform at acceptable levels. From a "bare minimum" standpoint, any computer that can run Windows Server 2003 can run Terminal Services. From a "practical" standpoint, however, there are different factors to consider relating to server hardware.

The basic idea here is that you're building a high-end workstation for your users. When designing your servers, throw the thoughts of file server out the window and start with what it would take for a high performing workstation. This generally amounts to going heavy on the processor and memory and light on the disk subsystem.

Before you buy a bunch of used IDE drives for your servers, let's expand on the phrase "light on the disk subsystem." You do not have to set up this server with five large SCSI drives configured in a RAID 5 array. A basic set of mirrored SCSI drives or maybe a small 3-drive RAID 5 array would suffice. Remember that since this is a workstation, no data should be stored on these servers and the amount of available drive space should not be an issue. See Chapter 5 for the full story about installing applications and needed drive space on your Terminal Servers.

Truthfully, properly sizing a Terminal Server is more of an exercise in the performance optimization of your overall Terminal Server environment than it is meeting a raw hardware requirements checklist. For this reason, the topic of Terminal Server optimization and server sizing deserves its own chapter (see Chapter 13).