A SAN (Storage Area Network) is a dedicated high-speed network that connects servers to centralised storage systems. Unlike NAS (Network Attached Storage), a SAN operates at block level, enabling higher performance. Common protocols include Fibre Channel and iSCSI. SANs are deployed in data centres where multiple servers need concurrent access to shared storage resources. In your ISMS you document the SAN as a critical infrastructure component in the asset register. Access controls, encryption, and redundant paths are standard security measures.