The bottom line – Sweex PU202 (eSATA PCI express card) based on Sil3515 chipset is not supported by nv_125.
Both cfgadm and prtdiag see that there is something in the slot:
Ap_Id Type Receptacle Occupant Condition
pcie1 pci-pci/hp connected configured ok
. . .
ID Status Type Description
— ——— —————- —————————-
2 in use PCI Express PCIE2
“format -e” does not see the disk connected to that card.