The –S option shows which LUNs were discovered on this target during enumeration.
For example:
# iscsiadm list target -S Target: iqn.2001-05.com.abcstorage:6-8a0900-37ad70401-bcfff02df8a421df-zzr1200-01 TPGT: default ISID: 4000002a0000 Connections: 1 LUN: 0 Vendor: ABCSTOR Product: 0010 OS Device Name: /dev/rdsk/c3t34d0s2
If you think a LUN should be listed but it is not, then check this log file.