Windows Server 2008: The Definitive Guide

Server Clustering

If an NLB cluster is too limited in functionality for you, investigate a true server cluster. In a true server cluster, a group of machines have a single identity and work in tandem to manage and, in the event of failure, migrate applications away from problematic nodes and onto functional nodes. The nodes of the cluster use a common, shared resource database and log storage facility provided by a physical storage device that is located on a hardware bus shared by all members of the cluster.

Tip

The shared data facility does not support IDE disks, software RAID (including Windows-based dynamic RAID), dynamic disks or volumes, the EFS, mounted volumes and reparse points, or remote storage devices such as tape backup drives.

Windows Server 2008 offers a single mixed-mode type of clustering that replaces the old quorum and majority node set clusters you might be familiar with from Windows Server 2003. In this new hybrid quorum model, there is a concept of "votes," and a cluster is by default designed to tolerate the loss of a single vote. Each node of a cluster gets a "vote," as does the storage source for a cluster; thus, if the quorum disk is lost, the cluster continues since only a single vote is no longer present. To re-create the old Windows Server 2003 model with a shared quorum disk as the absolute must-have resource for a cluster, you can simply assign a vote to the quorum disk (now called a witness disk) and no votes for each node of the cluster. Better still, ...