locks stop another partition of the cluster from being able to take ownership of the
witness and try to use its vote to make quorum. This is shown in Figure 7.2, along
with an odd number of vote scenarios showing why the witness is not required.
Figure 7.2 Quorum in a failover cluster
Windows Server 2012 R2 changed the recommendation always to configure the disk
witness or file share witness. It enhances the dynamic quorum feature introduced in
Windows Server 2012 to extend to the additional witness to give it a vote only if there
are an even number of nodes. If there are an odd number of nodes, the witness does
not get a vote and is not used.
A file share witness is simply a share on an SMB file server that is running Windows
Server 2003 or above and is on a node that is in the same forest as the cluster. The file
share should not be hosted on the actual cluster. If you have a multisite cluster, host
the file share witness on a server in a third site to avoid any dependence on one of the
two sites used by the cluster. A single file server can host file shares for different
clusters. The cluster object in Active Directory (cluster name object, or CNO) must
have full control on both the file share and the folder that the file share is sharing. A
good naming convention to use to avoid confusion for the share is FSW_<Cluster