Quorum Disk Selection Warning
The following warning message appears if you select the quorum disk (the last group in the list) on the Cluster Disk Selection screen. This warning applies to both Microsoft® Windows NT® 4.0 and Microsoft Windows® 2000:
It is strongly recommended that you not use the quorum group with SQL Server.
The quorum disk is a special resource in the Windows operating system. If you select the quorum disk, you may later want to restrict ownership of Microsoft® SQL Server™ to a subset of the cluster nodes. However, the quorum group owner list must include all of the nodes in the cluster.
For example, you may have a two-node cluster (Node1 and Node2) with SQL Server set to use the quorum disk group. If you then modify SQL Server to have only Node1 in the virtual server definition, the quorum disk group is prevented from failing over to Node2. In the event of a failure of Node1, the result is that you not only lose the virtual SQL Server, but the entire MSCS cluster.
This is true for Windows NT 4.0 only. In Windows 2000 the node list is ignored and the quorum disk group can fail over to any node in the cluster configuration. However, another issue may arise. In the previous example, there are no SQL Server program files available on Node2, but the cluster group can fail over to Node2. In this situation, SQL Server is unable to run on Node2 but the cluster group containing the quorum disk may fail over anyway, making your SQL Server unavailable.
For more information about the quorum disk, see the Windows NT documentation.