Services are useful only when they fulfill their role and are accessible. This is the key to high availability—keep services available. There is no point in purchasing a state-of-the-art iSCSI storage area network (SAN) with 30TB of storage for your organization’s data storage and then having it accessed via a single file server. If the file server is unavailable, there is no way to get to the data. The file services provided by the file server need to be highly available.
Windows Server 2008 provides two types of high availability: Network Load Balancing (NLB) and failover clustering. This chapter discusses these in detail; each tackles a different type of service that needs high availability.