FC Architecture

FC Fabric
  └── HBA Driver (lpfc / qla2xxx)
        └── SCSI Mid-Layer
              └── SCSI Disk (sdX — one per path)
                    └── dm-multipath
                          └── /dev/mapper/mpathX  ← application uses this
                                └── LVM (optional)

• Each FC path presents as an independent sdX device
• dm-multipath aggregates all sdX devices for the same LUN into /dev/mapper/mpathX
• Always target /dev/mapper/ devices, never raw sdX paths
• ALUA identifies preferred (active/optimized) vs. available (active/non-optimized) paths