How to read a DLT tape created with unknown method?

[Gus Mestousis]

I have a DLT tape that I need to extract to disk.
I'm not sure how it was created. So far I have tried the following:

# tar tvf /dev/rmt/1m
Tar: tape read error

# dd if=/dev/rmt/1m of=/yapi.tape.list
dd read error: I/O error
0+0 records in
0+0 records out

I also tried to use SAM to run frecover, but received...
Getting list of files...
frecover(2105): did not find expected file marker
frecover(5409): unable to read volume header
frecover(5418): not an fbackup volume; unable to read volume header
frecover(2105): did not find expected file marker

I also tried to scan the media with Omniback, but it didnt work.

Doeas anyone have any suggestions? Am I going about this all wrong?

Thanks,
Gus

[A. Clay Stephenson]

Your attempt using dd was the correct approach to determine the data format.

A little better approach might have been to specify a blocksize, e.g. bs=64k count=2
and attempt to read 2 blocks to a file. Because your dd failed completely, I suspect that you are trying to read imcompatible media. e.g data recorded on a DLT7000/8000 drive and now trying to be read with a DLT4000 drive.

Dd should have been able to read something regardless of the software used to back up the data.

[Gus Mestousis]

My drive is also a DLT7000, and it should be able to read the tape.
I assume the only way it would pose any issue is if it was created on a DLT8000 Drive.

Any thoughts?

[A. Clay Stephenson]

I'm betting that it was written on either a DLT 8000 or a SuperDLT drive; The SuperDLT can read any of the others. Until you can at least read a few blocks of data using dd, you are stuck. Note that after you suceed in reading data using dd you might still be unable to actually do anything useful depending upon the archiving software that was used.

[Sudhakar.J]

Hi,

While reading tape thru "tar" command u shld get checksum error if tape is written in a differnet format.But here it shows tape error.This could be of defective tape.Same thing in case of "dd" also.Check out ur tape condition.

regds
Sudhakar

[Gus Mestousis]

Just found out that the tape was created using a DLT8000 drive, but I only have a DLT7000 available. Do I have any chance at all at reading this?

[Stefan Farrelly]

Not unless you have a DLT8000 or get the system with the DLT8000 to create a special driver (man mksf) which can write the DLT tape in a non 8000 format (ie. in a DLT7000 format) then they can create a new tape and you will be able to read it on your DLT7000.

[Ravi_8]

Hi, Gus

whatever be the tape drive used to make tar backup, dd should be able to read atleast few bytes of data. I suspect the tape.