Troubleshooting guide

Appendix A, Functional Overview 259
Media Manager Functional Description
Barcode Operations
Barcode reading is mainly a function of the robot hardware rather than Media Manager.
When a robot has a barcode reader, it scans any barcode that may be on a tape and stores
the code in its internal memory. This associates the slot number and the barcode of the
tape in that slot. Media Manager determines that association for its own use by
interrogating the robot.
If a robot supports barcodes, Media Manager automatically compares a tape’s barcode to
what is in the volume database as an extra measure of verification before mounting the
tape.
Media Requests Involving Barcodes
A request for media that is in a robot that can read barcodes begins in the same manner as
other requests (see Figure 16). The Media Manager device daemon, ltid, determines the
location of the requested media ID by querying the Media Manager volume daemon, vmd.
The volume daemon then returns the information it has about the media, including: robot
number, robot type, host, slot, and barcode.
ltid includes the media ID and location information in a mount request to the robotic
daemon for the robot that has the media ID. This request causes the robotic daemon to
query the robot for the barcode of the tape in the designated slot (preliminary check to see
if the correct media is in the slot). The robot returns the barcode value it has in memory to
the robotic daemon, which compares this barcode with the value it received from ltid:
◆ If the barcodes don’t match, the robotic daemon informs ltid and a pending action
request (Misplaced Tape) appears in the Device Monitor (and xdevadm). An operator
must then insert the correct tape in the slot.
◆ If the barcodes match, the robotic daemon requests the robot to move the tape to a
drive. The robot then mounts the tape. At the start of the operation, the application
(for example, NetBackup) checks the media ID and if it also matches what should be
in this slot, the operation proceeds. For NetBackup, a wrong media ID, results in a
Media Manager Found Wrong Tape in Drive error (status code 93).