A single point of failure (SPOF) is a component whose failure halts an entire service or business process. Examples include a single switch with no redundancy, a database server with no failover, or a person who alone knows a critical password. You identify SPOFs through a failure analysis and eliminate them through redundancy, clustering, or knowledge documentation. In an ISMS, SPOF analysis is part of availability assurance. The business impact analysis helps you prioritise SPOFs by criticality.