WWN
also: WWPN, WWNN, World Wide Port Name, World Wide Node Name
WWN (World Wide Name) is a unique 64-bit or 128-bit identifier assigned to Fibre Channel and some other storage devices to enable persistent identification across reboots and configuration changes.
WWN is a globally unique identifier used primarily in Fibre Channel storage networks. Each HBA (Host Bus Adapter) port and storage device port is assigned a distinctive WWN that remains constant regardless of how the system is configured or restarted.
WWNs are typically displayed in hexadecimal format and come in two variants: WWPN (World Wide Port Name) for individual ports and WWNN (World Wide Node Name) for entire devices. Linux administrators use the lsscsi or cat /sys/class/fc_host/host*/port_name commands to view WWNs on Fibre Channel connected systems.
This persistent naming is essential in enterprise storage environments because it allows administrators to maintain consistent device mappings in /etc/fstab or multipath configurations even when hardware is moved between servers or storage arrays are reconfigured.