From：http://technet.microsoft.com/zh-cn/library/cc770620(v=ws.10).aspx
A failover cluster is a group of independent computers that work together to increase the availability of applications and services. The clustered servers (called nodes) are connected by physical cables and by software. If one of the cluster nodes fails, another node begins to provide service (a process known as failover). Users experiencea minimum of disruptions in service.
This guide describes the new quorum options in failover clusters in Windows Server 2008 and provides steps for configuring the quorum in a failover cluster. By following the configuration steps in this guide, you can learn about failover clusters and familiarize yourself with quorum modes in failover clustering.
In Windows Server 2008, the improvements to failover clusters (formerly known as server clusters) are aimed at simplifying clusters, making them more secure, and enhancing clusterstability. Cluster setup and management are easier. Security and networking inclusters have been improved, as has the way a failover cluster communicates with storage. For more information about improvements to failover clusters, see http://go.microsoft.com/fwlink/?LinkId=62368.
【 Note：There are too much content, but I just copy some sections. See more, please go to origianal web 】
Steps for changing the quorum configuration in a failover cluster
1. 要打开“故障转移群集”管理单元，请依次单击“开始”、“管理工具”，然后单击“故障转移群集管理”。 (如果出现“用户帐户控制”对话框，请确认所显示的是您要执行的操作，然后单击“继续”。)
2. 如果故障转移群集管理管理单元中没有显示要配置的群集，请右键单击控制台树中的“故障转移群集管理”，单击“管理群集”，然后选择或指定需要的群集。
3. With the cluster selected, under Actions, click More Actions,and then click Configure Cluster Quorum Settings.
4. Click Next.The following illustration shows the wizard page that displays for a clusterwith an even number of nodes. Note that the text on this page varies, depending on whether the cluster has an even number or odd number of nodes. To view more information about the selections on this page, at the bottom of the page, click More about quorum configurations.
5. Select aquorum mode from the list. For more information, see Choosing the quorum mode for a particular cluster, earlier in this guide.
6. Click Next and then go to the appropriate step in this procedure:
If you chose Node Majority, go to the last step in this procedure.
If you chose Node and Disk Majority or No Majority, go to the next step in this procedure.
If you chose Node and File Share Majority, skip to step 8 in this procedure.
7. If you chose Node and Disk Majority or No Majority,a wizard page similar to the following appears. (For No Majority,the title of the page is Select Storage Resource.) Select thestorage volume that you want to use for the disk witness (or if you chose NoMajority, for the quorum resource), and then skip to step 9. Forinformation about the requirements for the disk witness, see Requirementsand recommendations for clusters using Node and Disk Majority.
If you change disk assignments on this page, the former storage volume is no longer assigned to the core Cluster Group and instead goes back to AvailableStorage.
8. If you chose Node and File Share Majority, the following wizard pageappears. Specify the file share you want to use, or click the Browse button and use the standard browsing interface to select the file share. Forinformation about the requirements for the file share, see Requirements and recommendations for clusters using Node and File Share Majority.
9. Click Next.Use the confirmation page to confirm your selections, and then click Next.
10. After the wizard runs and the Summary page appears, if you want to view a report of the tasks that the wizard performed, click View Report.
