Restoring a Unix Tar File with Ubuntu

I have all of these old DDS3 and DDS4 tapes that I need to restore the files off of. The only information that I really know is that they were put on the tapes about 10 to 20 years ago using Digital Unix. They are in a Tar file format.

I have been using Ubuntu 13.04 to try to restore these files but I've had zero success so far. I have really no idea how to get these files off of here. A couple of commands that we've tried in terminal are:

/media/archive/SCSI/Linux$ sudo dd if=/dev/st0 ibs=128k | tar -vxf -
sudo tar -xzf /dev/st0 /media/archive/SCSI/Linux

/media/archive/SCSI/Linux is what I am trying to restore to and st0 is the Tape Drive name.

Please help me out! I'm only an intern!
Thanks

Solution 1:

Use dd to pull all the info off the tapes, and then experiment with copies of the files. Tapes are fragile after 20 years, so assume media is cracking and oxide is flaking off.

Examine the first 100 characters of the file, it should be recognizable as a tar header, if it looks scrambled, but not binary (encrypted), try dd with some of the byte swapping switching, again just the first characters until you get the right combination, then you can dd with those switches to tar.

If the header looks encrypted, try the tar z with the various byte swapping on dd, then try uudecode, (on a copy of the file, then dd byte-swapping, first few hundred...) Try unzip on the file. When you can see the header, then apply to the whole file.