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RHEL 4.x or earlier, to find the WWN run the cat /proc/scsi/adapter_type/n command, where adapter_type is the host adapter type, and n is the host adapter number for your card. In most cases, the adapter type is qla2xxx.
cat /proc/scsi/adapter_type/<n>
RHEL 5.x or later, the adapter WWN information can be found:
cat /sys/class/scsi_host/hostn/device/fchost\:host<n>/port_name
lspci | grep -i fibre 08:00.0 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02) 08:00.1 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)