This object reports whether this target entry was actually discovered live on the fabric by the SCSI instance (true) versus having been added from some other source such as manual configuration (false), and per the desc it is read-only precisely because discovery status is not something an admin can simply declare. An admin auditing which configured targets are genuinely present and reachable right now versus merely defined in configuration but not currently visible uses this flag to tell the two apart at a glance. A target entry showing configured=true but discovered=false would mean it is authorized in policy but not currently seen on the fabric - worth checking if that is expected (e.g., the array is powered down for maintenance) or a problem.