What could cause a tape drive to drop off-line in Windows NT 4.0/2000/XP/.NET?
When a tape drive drops offline there most likely be one of the following errors in the Event Viewer System logs:
Event ID: 9
Source: [scsi miniport driver]
Description: The device, \Device\Scsi\[scsi miniport driver], did not respond within the timeout period.
Event ID 9 error is the result of a SCSI command timeout. If the tape drive has to retry many times the command time-out value to may be met. The tape drive Write / Read quality will need to be verified. You can use the Sony Tape Utility to check your tape drive.
Veritas Backup Exec NT / Win2K has a known issue with Win2K driver patches bnt86idrv31_243823.exe / bnt86idrv32.exe. Both patches will set Write command time-out to 6 minutes and Read command time-out to 3 minutes. You will need to apply bnt86idrv36a_256251.exe driver patch which increases Write and Read command time-out to 15 minutes.
http://seer.support.veritas.com/docs/256251.htm
It is highly possible that other Tape Backup applications might have similar command time-outs so it is important to check the Event Viewer System logs.
Event ID: 11
Source: [scsi miniport driver]
Description: The driver detected a controller error on Device\ScsiPortX.
Event ID 11 is error is different from a SCSI command time-out. This error could be a result of a hardware problem, a malfunctioning device, poor cabling, or termination issues.