Logical Unit Number (LUN) A logical unit number (LUN) is a unique identifier for designating an individual or collection of physical or virtual storage devices that execute input/output (I/O) commands with a host computer, as defined by the Small System Computer Interface (SCSI) standard. SCSI is a widely implemented I/O interconnect that commonly facilitates data exchange between servers and storage devices through transport protocols such as Internet SCSI (iSCSI) and Fibre Channel (FC)...