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LUN Not Visible to the Host
The LUN exists in ONTAP, but the host cannot discover it or has lost all usable paths.
What ONTAP is telling you
Host visibility requires the LUN to be online and mapped to an igroup containing the correct initiator, plus a working FCP/iSCSI service, LIF/session, fabric or IP path, and host rescan/multipathing.
How to confirm
lun show -vserver <svm> -path </vol/volume/lun> -fields state,mapped,serial-hex
lun mapping show -vserver <svm> -path </vol/volume/lun>
lun igroup show -vserver <svm> -instance
network interface show -vserver <svm> -data-protocol fcp,iscsi
vserver iscsi connection show -vserver <svm>
vserver fcp initiator show -vserver <svm>Output shape: LUN output establishes online/mapped state and identity; mapping output gives igroup and LUN ID; igroup output gives protocol, OS type, and initiators; session/initiator output proves whether the host reaches the target.
The fix
Correct the first missing link: bring the intended LUN online, map it to the verified igroup, correct initiator membership/OS type, or restore target LIF/fabric/session connectivity. Then rescan using the host vendor's documented procedure and verify multipath identity before mounting or writing.
How to prevent it
Record initiator-to-igroup mappings, use supported host utilities/multipathing, zone redundant FC fabrics or provide redundant iSCSI paths, and validate every path after SAN changes.
Sources and version relevance
Commands and claims are limited to material already represented in the Black Box archive. CLI links target the archived ONTAP 9.19.1 reference; fields and availability can differ by release. Check your ONTAP version and on-cluster command ? before production use.
Related Black Box pages: FC/FCP · iSCSI · SAN multipathing · all troubleshooting guides
Related advisory: none identified in the archive for this operational symptom.