Windows Server 2003 doesn't introduce many new clustering concepts, but it does extend clustering capabilities throughout most of the Windows Server 2003 family. New clusterable applications and services are also available, making creating high-availability network services easier.
One of the most important changes to clustering is that the Cluster Service is now available on three of the four Windows Server 2003 editions: Standard, Enterprise, and Datacenter. Cluster Service clusters can also contain up to eight nodes, double the number of Windows 2000. Note that Standard Edition supports only two-node clusters.
Windows's other major clustering technology, Network Load Balancing (NLB), is now available in four editions of Windows Server 2003, not just Enterprise (formerly Advanced) and Datacenter, as was the case in Windows 2000. Network Load Balancing is a crucial technology for deploying scalable, high-workload Web sites and .NET Web Services, so it's easy to understand why Microsoft chose to include the technology in all editions.
Both of these clustering technologies have been available in prior versions of Windows. However, some of the details of their operation, as well as how they're managed, have been updated for Windows Server 2003. We'll cover both technologies in this chapter, including detailed, step-by-step instructions for using them.