Bacula Cannot Open the Device

If you get an error message such as:

dev open failed: dev.c:265 stored: unable to open
device /dev/nst0:> ERR=No such device or address

the first time you run a job, it is most likely due to the fact that you specified the incorrect device name on your Archive Device.

Sometimes the tape handler gets confused. This can happen if your tape drive door is locked (Bacula locks it when writing a tape), and Bacula crashes or some other problem occurs. After this kind of a problem, the kernel driver will not recognize that a tape is loaded and you may see messages such as:

19-Sep 16:39 groschat-sd JobId 16072: Warning: mount.c:219 Open of tape
device "LTO9-Drive" (/dev/tape/by-id/scsi-3500143801403cf22-nst) Volume
"AAJ372" failed: ERR=tape_dev.c:162 Unable to open device "LTO9-Drive"
(/dev/tape/by-id/scsi-3500143801403cf22-nst): ERR=No medium found

19-Sep 16:39 groschat-sd JobId 16072: Please mount append Volume "AAJ372"
 or label a new one for:
      Job:          Rufus.2016-09-19_16.34.22_03
      Storage:      "LTO9-Drive" (/dev/tape/by-id/scsi-3500143801403cf22-nst)
      Pool:         Default
      Media type:   LTO-4

in that case, the best thing to do is unload the tape by hand with:

(stop Bacula)
mtx -f /dev/sgx unload
(restart Bacula)

where you replace /dev/sgx by your scsi control device name.