cdi_open failed, the device file name specified is busy for device /dev/rmt/4debn

BTW - it should read "Usually, NW will change the device status to 'service mode'..."

This general message refers to the device descriptor file /dev/rmt/4debn .

Usually, NW will change the device status to 'suspect' if the amount of write retries would have reached the max. number of consecutive errors for the device (default=20). Be aware that such (still) will take place if run a 'batch label' job to the same device (if you try to consecutively label this number of virgin (new) tapes). The counter will be reset with the first successful read/write process.

To bring a device out of service mode, you usually disable and re-enable it. This should clear the problem. If it persists, then there might be an issue with the drive and/or the media. Maybe device cleaning will help.

Hi @bingo.1 

Thank you for your quick answer

We will proceed to replace the drive by a new one. because the tape library has got 3 other working drives and jobs run correctly on these drives. (thats why we dont think that it is a problem with tapes or labels).

Can you please exlpain why the status of the drive is service mode in NW while it is ok and operational in the tape library. 

Thank you very much

Actually I cannot tell you the reason why without looking deeper at the system (and logs). Maybe this paragraph from the Admin Guide will help you:

Device Service mode
Use the service mode setting to take a device offline temporarily. Service mode differs from the disabled state in that the nsrmmd process is not stopped.
While a device is in service mode, save or recover sessions that are either in process or pending are completed. No new sessions are assigned to the device while it is in service mode.
Although a drive in service mode is taken out of the collection of drives that the NetWorker software can select for automated operations, the drive is available for some manual operations that use the nsrjb or nsrmm command with the -f option. For more information, refer to the NetWorker Command Reference Guide or the UNIX man pages.
The device might also go into service mode, rather than become disabled, if consecutive errors occur in excess of the maximum consecutive error count specified for the device. This means that if there are no hardware issues, the tape can be ejected and used in other drives. Media handling errors on page 134 provides more information about how to set the maximum consecutive error count.

NOTE: The drive must be manually reset to Enabled for the NetWorker software to use the device again.