Backup to an LTO-6 fails with an 'HARDWARE ERROR [4] - ASC 03 ASCQ 02' error. (4037491)

Backup to an LTO-6 fails with an 'HARDWARE ERROR [4] - ASC 03 ASCQ 02' error.

The following messages and errors were within the NetVault logs:

1] Error   2015/02/03 12:56:01   51   Media   ARCHIVE4   Failed to write header

With sub text:
TAPESCSI:03016   13       0 125601 Write header to tape (bs =65536, 65536) (BEGIN)
SCSI    :03016   14       0 125601 CMD WRITE [ 0a 01 00 00 01 00  ]
SCSI    :03016   16       0 125601 CMD STATUS 'CHECK CONDITION' [2]
SCSI    :03016   17       0 125601 CMD SENSE KEY 'HARDWARE ERROR   ' [4] - ASC 03 ASCQ 02
SCSI    :03016   18       0 125601 CMD SENSE INFO 'EXCESSIVE WRITE ERRORS'
SCSI    :03016   20       0 125601 CMD RETURN VALUE 2
TAPESCSI:03016   14       0 125601 Write header to tape (END)
DEVMGR  :03016   84       1 125601 Write header FAILED

2] Error   2015/02/03 13:02:18   0   Media   ARCHIVE4   Command failed, re-initializing driver

With sub text:
TAPESCSI:03016    2       0 130218 Close Device
SCSI    :03016   14       0 130218 CMD PREVENT/ALLOW MEDIA REMOVAL [ 1e 00 00 00 00 00  ]
CAMNT   :03016   38       1 130218 (NT) Device I/O control failed (0,2)
CAMNT   :03016   40       1 130218 (NT) Windows NT Kernel SCSI Passthrough unrecoverable NT kernel error
CAMNT   :03016   41       1 130218 (NT) SPT  000017f560:  2c 00 00 00 00 00 06 18 02 00 00 00 00 00 00 00
CAMNT   :03016   41       1 130218 (NT) SPT  000017f570:  84 03 00 00 00 00 00 00 30 00 00 00 1e 00 00 00
CAMNT   :03016   41       1 130218 (NT) SPT  000017f580:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
CAMNT   :03016   42       1 130218 (NT) SCMD 0000872b7c:  1e 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
SCSI    :03016   15       0 130218 CMD failed: errno 2

These are all hardware issues i.e. outside of NVBU (writing and a SCSI communication problem) and you will need to consult your hardware vendor and supply the above logs.
We also advise to clean the tape library drive Read/Write Heads to remove any tape contamination.
This KBA advises how to setup cleaning media in NVBU and make sure that the tape library cleaning is disabled. Otherwise NVBU will think that the cleaning media is a normal tape and try to write to it:

https://support.quest.com/netvault-backup/kb/78529

The “Command failed, re-initializing driver” error is a generic SCSI Bus error which reports back to NetVault from the Operating System i.e. is outside of NetVault (SCSI Protocol messages are also the same on FC, as the same protocol) and would advise to check anything from the NetVault Server Motherboard, SCSI/FC card, SCSI/FC card firmware, SCSI/FC cables, SCSI terminators, tape library, drives(s), tape library firmware and drive(s) firmware version(s). It might be worth checking the power cable is securely in, so that it isn’t arching. Does your SCSI Card have some sort of RAID Controller on it as well? In which case might be worth changing to a non-Raid SCSI Card. Adaptec is the preferred brand.

Have you made sure that the tape library web interface has the Mode set to Random Mode and NOT Sequential Mode (as this Mode is not supported):

https://support.quest.com/netvault-backup/kb/128130

Have you setup the tape library for Multipathing? As this is NOT supported:

https://support.quest.com/netvault-backup/kb/79455

Note: Whenever you make any hardware/firmware/cable changes and/or upgrades, then you also have to perform the following steps to make sure that the SCSI Protocol Communication Channel has been re-established (otherwise you will experience media/device/job issues):

a] Make a screenshot of the tape library name and configuration settings, so that the device can be re-added with the same tape library name and configuration settings.
b] Remove the tape library in NetVault Device Management.
c] Reboot the NetVault Server.
d] Re-add the tape library, making sure that the same tape library name and configuration settings are implemented.

Note: Please check the NetVault Backup - Supported VTLs, Libraries, Tape and Optical Drives compatibility guide on the following link to make sure that your tape library/drive are supported and that the library/drive firmware versions are above the minimum supported version too:

https://support.quest.com/netvault-backup/technical-documents