The scsi_address(9S) structure contains the following fields:
scsi_hba_tran_t *a_hba_tran; /* HBA transport vectors */ u_short a_target; /* Target on SCSI bus */ u_char a_lun; /* Lun on that Target */
a_hba_tran is a pointer to the scsi_hba_tran(9S) structure, as allocated and initialized by the HBA driver. If SCSI_HBA_TRAN_CLONE was specified as the flag to scsi_hba_attach_setup(9F), a_hba_tran points to a copy of that structure.
a_target identifies the SCSI target on the SCSI bus.
a_lun identifies the SCSI logical unit on the SCSI target.