NFS servers are a common form of shared filesystem infrastructure, and can be used as a storage repository substrate for virtual disks.
As NFS storage repositories are shared, the virtual disks stored in them allow VMs to be started on any server in a resource pool and to be migrated between them using XenMotion.
When you configure an NFS storage repository, you simply provide the hostname or IP address of the NFS server and the path to a directory that will be used to contain the storage repository. The NFS server must be configured to export the specified path to all servers in the pool