A cluster witness must be configured for a two-node cluster. Microsoft recommends configuring a cluster witness for a four-node Azure Stack HCI cluster. Cluster witness configuration helps maintain a cluster or storage quorum when a node or network communication fails and nodes continue to operate but can no longer communicate with one another.
A cluster witness can be either a file share or a cloud-based witness.
For information about configuring a cloud-based witness, see Cloud-based witness.