Command failed, re-initializing driver (4045159)

The Command failed, re-initializing driver error message indicates that the NetVault device manager process has received no response from the device from a standard SCSI command.
The device manager process is re-spawned in an attempt to re-connect to the device. This indicates a breakdown in SCSI communication between the NetVault process & the target device and is caused by a fault within the SCSI subsystem.
 

Please see the following video:

Software side troubleshooting involves:

1) For devices connected to Windows servers, otherwise skip to step two. 

A.    Windows 2003, check that the “Removable Storage” service has been stopped and set to disabled.

B.    Windows 2008 and above does not use “Removable Storage” service.

2) Disable any other backup application installed on the NetVault server or SmartClient Machine.

3) The SCSI termination of the library and/or drive and all the interconnecting cabling.
4) Verify that you have the latest SCSI driver and that no vendor specific Tape or Library drivers have been loaded.

5) Ensure that your block size does not exceed 64 KB, as most Windows SCSI drivers can't handle anything higher than that.

6) Also verify that you have added your drives in the correct order in NetVault Device Management. Refer to solution "How to allocate drives to the correct drive bays" (SOL79070).

7) This can problem can result from a corrupt device tree - please apply the solution "How to recreate a device tree in NetVault" (SOL79547)

Contacting your hardware vendor if these steps cannot resolve the problem.
Show them the errors detailed in the NetVault logs, in particular the SCSI errors.