Running the scan -tape command shows Device Names as "-" and displays no st devices

Example:

Device Name  :"-"
Passthru Name: "/dev/sg3"
Volume Header: ""
Port: -1; Bus: -1;Target: -1; LUN: -1
Inquiry    : "STK    T9940B          1.36"
Vendor ID  :"STK     "
Product ID :"T9940B          "
Product Rev: "1.36"
SerialNumber: "479002024500"
WWN          : ""
WWN IdType  : 0
Device Identifier: ""
Device Type    :SDT_TAPE
NetBackup Drive Type: 10
Removable      :Yes
Device Supports: SCSI-3
Flags : 0x0
Reason:0x10000



Troubleshooting:

# mt -f /dev/nst1 status
mt:/dev/nst1: Input/output error
# mt -f /dev/nst2 status
mt: /dev/nst2:Input/output error


lsmod |grep -wst
st                    148640  0
scsi_mod              291816  13


Solution:  Aslong as the st module is running. This is a Fibre communication issue .Recommendation is Reboot the Server