Running CENTOS 6.3, I have a DDS tape drive connected to the workstation.

I know the tape drive is connected and talking to the computer, I can put a blank DDS tape into the unit and write to that tape, extract from that tape, rewind, eject....ect....ect....

I received a tape at work that needs data extracted from it. I'm pretty confident that the data is actually on the tape, but I can't seem to do anything with it.

Block size should be 10240, which I set it to.

mt -f /dev/nst1 status
SCSI 2 Tape Drive:
File Number=0 block number=0 partition=0
Tape block size 10240 bytes. Density code 0x24 (DDS-2)
Soft error count since last started=0
General status bits on (41010000):
BOT ONLINE IM_REP_EN

tar -xvf /dev/nst1
tar: /dev/nst1: Cannot read: Input/output Error
tar: at beginning of tape, quitting now
tar: error is not recoverable, exiting now

After I get this error I can't do anything with the tape, even check status or rewind.

When I first put the tape in, I can rewind it, set block, check status....ect...

After the tar command, when I try anything like

mt -f /dev/nst1 rewind
/dev/nst1: Input/output error



Anyone have any ideas on things I could try?

Thanks in advance!!
Ryan

The DDS standard has gone through several versions. The newer versions of DDS are not necessarily compatible with older versions. Check to see if the tape drive that created the tape in question uses the same version of the DDS standard as the tape drive that you are using to try to read the tape.

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Steve Stites

What sort of DDS tape drive have you? There are drives which write at higher density than the original DDS format, i.e. DDS2, DDS3, DDS4 and are labled as such.. You will be unable to read a higher formatted tape on a lower spec's drive ( if you see what I mean)
Tape cartridges are also labled DDS2, DDS3, etc.
You could also have head misalignment between your drive and your work's drive. DDS drives work like the old VHS video tape recorders using a scanning head which occasionally gave tracking errors and you got a snowy picture.
Can you read the tapes written on your drive at your work?

Play Bonny!

Thank you for the response!

I'm not sure on a model number/type for my DDS drive. Its a Sony. The tape being used is a DDS-2 tape. I can and have used DDS-2 tapes in this drive. So I don't think a mismatch in density is the issue.

I only have one DDS drive, the data is recorded onto the tape off-site at a location that is pretty remote - I can't get to their hardware in other words.

I can write to the drive locally and pull the data back off.

Any ideas?

Thanks again,
Ryan

Does anything relevant appear in /var/log/messages when you try to read these tapes?

In that case I'd reckon that you're not going to find any software problem. It looks like there's possibly a head alignment mismatch between your and the "work" DDS2 drive.

The only easy thing I can think of is getting someone at your work to run a cleaning tape through the drive. Use a new "Still in the cellophane" cleaning tape if possible. DDS cleaning tapes use a different section of tape on each clean, the tape eventually all ends up on the take up spool of the cassette (RHS as you'd load it I think) Something like 20 uses then you throw it away.
If the drive needed cleaning it would generally show an amber "Clean me" led, can you have this checked on the work drive?

If it is an alignment problem, you won't cure it unless you find out which of the two drives is misaligned, then replace it.

Play Bonny!