[SOLVED] Cant backup to tape

sree.m · 03-16-2012, 05:43 AM

Hi ,

I have been trying to take backup to my scsi tape drive, but m afraid i cant do the backup uing either dump or tar utility. Both returns "backup completed" though i cannot see any files appended in the tape catridge after the backup. The status of tape drive is as follows

# mt -f /dev/st0 status
SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 0 bytes. Density code 0x42 (unknown).
Soft error count since last status=0
General status bits on (41010000):
BOT ONLINE IM_REP_EN

But giving a 'tell' throws this

# mt -f /dev/st0 tell
/dev/st0: Input/output error

Can somebody suggest me some steps to go ahead from this point ??

regards,
Sree

TenTenths · 03-16-2012, 06:12 AM

Not all tape drives support "tell"

The BOT at the bottom of your status line shows that the drive is currently at the beginning of the tape.

How exactly are you doing your backup and what is the tape device.

(I'm doing a fair bit with tapes at the moment as I'm having to work with a nice new LTO4 8 tape changer)

TenTenths · 03-16-2012, 06:20 AM

If you're just wanting to check the tape is working etc. then you can do a short backup of your /etc folder and then check it's on the tape.

To backup to the tape: You'll see that before and after the tar the tape will show BOT, that's because using /dev/st0 causes the tape to rewind after each operation.

Code:

mt -f /dev/st0 status
tar -cvf /dev/st0 /etc
mt -f /dev/st0 status

You can get a listing of what's on the tape with these commands, the first will show you the contents, and the second will show you that after the tar the tape has rewound.

Code:

tar -tf /dev/st0
tape -f /dev/st0 status

If you replace /dev/st0 with /dev/nst0 then it tells the tape drive NOT to rewind.

sree.m · 03-16-2012, 07:05 AM

Thanks for your response.

Since i was not using /dev/nst0 it was rewinding the tape after every backup hence i couldnot see the backup files appended one after the other.

The status after 'dump' backup now is

[root@htbdb1 ~]# mt -f /dev/nst0 status
SCSI 2 tape drive:
File number=1, block number=0, partition=0.
Tape block size 0 bytes. Density code 0x42 (unknown).
Soft error count since last status=0
General status bits on (81010000):
EOF ONLINE IM_REP_EN

Now i got that point. I gotta appreciate this nice work of guiding me through the right way. Thanks.

regards,
Sree