Do you offer to do so? For example three nodes with their local storage (hdd), NFS mount in /etc/fstab, in Proxmox's WEB-interface storages added as Direcotry:
Node #1:
/var/lib/vz01 - local fs
/var/lib/vz02 - nfs to node2:/var/lib/vz02
/var/lib/vz03 - nfs to node3:/var/lib/vz03
Node #2...