Getting 'reservation conflict' errors for tape devices used by NetBackup application

Issue

• Symantec NetBackup slave server controls the tape robot for the NetBackup service (one master server and 4 other slaves). After the addition of new tape devices and system reboot, we are getting following 'reservation conflict' errors in logs:

  kernel: st 6:0:4:0: reservation conflict
  avrd[773]: Reservation Conflict status from IBM.ULT3580-xxxx (device 8)
  kernel: st 6:0:4:0: reservation conflict
  kernel: st 6:0:4:0: reservation conflict
  kernel: st 6:0:4:0: reservation conflict
  kernel: st 6:0:4:0: reservation conflict
  kernel: st 6:0:4:0: reservation conflict
  kernel: st 6:0:4:0: reservation conflict
  kernel: st 6:0:4:0: reservation conflict
  avrd[773]: Reservation Conflict status from IBM.ULT3580-xxxx (device 9)
  [...]