Hi John, thanks a lot for all the suggestions - will let you know.
Seems 'scan' works fine and reports on all tape drives (14 in total):
Device Name : "/dev/rmt/0cbn"
Passthru Name: "/dev/sg/c0tw500507630f9a1902l0"
Volume Header: ""
Port: -1; Bus: -1; Target: -1; LUN: -1
Inquiry : "IBM 03592E05 1E0D"
Vendor ID : "IBM "
Product ID : "03592E05 "
Product Rev: "1E0D"
Serial Number: "000007877009"
WWN : ""
WWN Id Type : 0
Device Identifier: "IBM 03592E05 000007877009"
Device Type : SDT_TAPE
NetBackup Drive Type: 10
Removable : Yes
Device Supports: SCSI-3
Flags : 0x0
Reason: 0x0
------------------------------------------------------------
Device Name : "/dev/rmt/1cbn"
Passthru Name: "/dev/sg/c0tw500507630f9a1903l0"
Volume Header: ""
Port: -1; Bus: -1; Target: -1; LUN: -1
Inquiry : "IBM 03592E05 1E0D"
Vendor ID : "IBM "
Product ID : "03592E05 "
Product Rev: "1E0D"
Serial Number: "000007879308"
WWN : ""
WWN Id Type : 0
Device Identifier: "IBM 03592E05 000007879308"
Device Type : SDT_TAPE
NetBackup Drive Type: 10
Removable : Yes
Device Supports: SCSI-3
Flags : 0x0
Reason: 0x0
.....
.....