Changing the tape library settings to sequential mode throws the tape library offline. (4036617)

Changing the tape library settings to sequential mode throws the tape library offline.

The following error messages are written to the NetVault logs:

1] Error   2014/06/23 08:19:04   0   Media   BCKUPCS101   (BCKUPCS101: SL_00L4U78T0700_LL0 (IBM 3573-TL)) Load media in 'DRIVE 1:BCKUPCS101' failed

With sub text:
SCSI       17       0  71904 CMD SENSE KEY 'NOT READY   ' [2] - ASC 3a ASCQ 00
SCSI       18       0  71904 CMD SENSE INFO 'MEDIUM NOT PRESENT'
SCSI       20       0  71904 CMD RETURN VALUE 2
TAPESCSI   41       0  71904 No Media in device
TAPESCSI  114       0  71904 Do A Load Media (END)
TAPESCSI   45       0  71904 Load Media (END)
DEVMGR     40       1  71904 Failed to load device
DEVMGR      2       0  71904 Send Manager Msg (BEGIN)

2] Error   2014/06/23 08:19:04   0   Media   BCKUPCS101   'BCKUPCS101: SL_00L4U78T0700_LL0 (IBM 3573-TL): DRIVE 1:BCKUPCS101' has gone down
3] Error   2014/06/23 09:18:34   0   Media   BCKUPCS101   (BCKUPCS101: SL_00L4U78T0700_LL0 (IBM 3573-TL)) Move media 'EWM DEV & QAS' (DYP654L4) <sap_ewm_system> from 'SLOT  2' to 'DRIVE 1:BCKUPCS101' failed

With sub text:
CHGSCSI    22       0  81832 CMD MOVE MEDIUM [ a5 00 00 01 10 01 01 00 00 00 00 00  ]
CAM         4       0  81834 Sense Key: '5', Ext Sense: '3b', Qual: 'd'
CHGSCSI    24       0  81834 CMD STATUS 'CHECK CONDITION' [2]
CHGSCSI    25       0  81834 CMD SENSE KEY 'ILLEGAL REQUEST' [5] - ASC 3b ASCQ 0d
CHGSCSI    74       0  81834 CMD SENSE INFO 'DESTINATION ELEMENT FULL'
CHGSCSI   204       0  81834 tDevRet = DEV_INVALID_REQUEST

4] Error   2014/06/23 09:18:34   0   Media   BCKUPCS101   'BCKUPCS101: SL_00L4U78T0700_LL0 (IBM 3573-TL): DRIVE 1:BCKUPCS101' has gone down
5] Error   2014/06/23 10:29:07   0   Media   BCKUPCS101   (BCKUPCS101: SL_00L4U78T0700_LL0 (IBM 3573-TL)) Position media in 'DRIVE 2:BCKUPCS101' failed

With sub text:
SCSI       16       0  92907 CMD STATUS 'CHECK CONDITION' [2]
SCSI       17       0  92907 CMD SENSE KEY 'NOT READY   ' [2] - ASC 3a ASCQ 00
SCSI       18       0  92907 CMD SENSE INFO 'MEDIUM NOT PRESENT'
SCSI       20       0  92907 CMD RETURN VALUE 2
TAPESCSI    4       0  92907 Position to segment return (2) (END)
DEVMGR     96       1  92907 Position segment failed

6] Error   2014/06/23 11:03:46   0   Media   BCKUPCS101   Command failed, re-initializing driver

With sub text:
TAPESCSI    2       0 100346 Close Device
LIST       17       0 100346 FALSE = ListWalk(0x80c3768, 0xf754381a, 0xffc4fea0)
SCSI       14       0 100346 CMD PREVENT/ALLOW MEDIA REMOVAL [ 1e 00 00 00 00 00  ]
CAM       222      19 100346 Failed to send SG_IO ioctl (No such device)
SCSI       15       0 100346 CMD failed: errno 19

7] Error   2014/06/24 01:30:07   2237   Media   BCKUPCS101   (BCKUPCS101: SL_00L4U78T0700_LL0 (IBM 3573-TL)) Move media 'EWM PRD System TAPE2' <sap_ewm_prd> from 'DRIVE 2:QEWCS101' to 'SLOT  7' failed

With sub text:
CHGSCSI    22       0   3006 CMD MOVE MEDIUM [ a5 00 00 01 01 01 10 06 00 00 00 00  ]
CAM         4       0   3007 Sense Key: '5', Ext Sense: '53', Qual: '3'
CHGSCSI    24       0   3007 CMD STATUS 'CHECK CONDITION' [2]
CHGSCSI    25       0   3007 CMD SENSE KEY 'ILLEGAL REQUEST' [5] - ASC 53 ASCQ 03
CHGSCSI    74       0   3007 CMD SENSE INFO 'MEDIUM REMOVAL PREVENTED BY DATA TRANSFER ELEMENT'
CHGSCSI   204       0   3007 tDevRet = DEV_INVALID_REQUEST

8] Error   2014/06/24 01:32:17   2237   Media   BCKUPCS101   (BCKUPCS101: SL_00L4U78T0700_LL0 (IBM 3573-TL)) Drive 'DRIVE 1:QEWCS101' has incorrect media ''Tape 2' (DYP523L4) <sap_pi_prd>'

Sequential Mode setting is not supported, as NetVault Backup needs to have 100% control of all its backup devices, otherwise backup/device/media issues will occur.

As per the following KBA we mention that Sequential Mode and Multipathing are NOT supported, as NetVault Backup needs to have 100% control over its devices:

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

Here is some further information about the modes…

Random: In random mode, the library allows the server's (host's) application software to select any data cartridge in any order.

Sequential: In sequential mode, the library's firmware predefines the selection of the cartridges. After initialization, the firmware causes the library to select the first available cartridge found (counting from the I/O Station through the last slot in your library) for loading into the drive.

The following KBA also mentions that Random Mode is the preferred selection:

https://support.quest.com/netvault-backup/kb/81148