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Hello, I have a SUSE 10 system (of course, tar is installed) and I am trying to do data recovery from some old tape drive for a local machine shop. ...
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  1. #1
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    GNUtar reading SGI IRIX tar??


    Hello, I have a SUSE 10 system (of course, tar is installed) and I am trying to do data recovery from some old tape drive for a local machine shop. Their tapes were written with an SGI Personal Iris (running some version of IRIX). From what I have read, SGI's tar is a bit different than GNUtar, and I am not able to read the archives on these tapes. Tar just says 'this doesn't appear to be a tar archive' and that the files 'use obsolescent base-64 headers'. Is there any way that I will be able to extract these archives? I tried using 'dd' but 80% of the tapes fail out with I/O errors, while the other 20% dumps a single binary file, and I have no idea what to use to split the file into the original files that were backed up. PLEASE HELP!!

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    Problem solved. I ended up having to use dd to extract the data and pipe it through tar. However, what made this work was byte-swapping. Online, I found a newsgroup thread from 1991, concerning reading SGI IRIX written tapes on a Sun system. I guess SGI tar is different somehow than GNUtar. Now, I AM trying to read IRIX written tapes, but not on a Sun. I am trying to read them with Suse 10. Well, just for grins, I tried the commands listed for Sun, and they worked. So, now, dd is taking the data, swapping the bytes, then piping the data through tar, and everything is extracting just fine.

    In case you are curious, the command is 'dd if=/dev/st0 conv=swap ibs=512 obs=512 | tar -xvBf -'

    'ibs' is determined by the tape's block size, shown by 'mt -f /dev/st0 status'.

    'obs' is the same as 'ibs'.


    ***NOTE: When you use 'tar -xxxx "-"' it dumps the data WHERE YOU ARE. I found this out the hard way, as many of the files in my /root/ were replaced by IRIX files (including my /root/bin/ directory) and I may need to reinstall Suse again, as I am not savvy enough to know how to 'rebuild'. If you try to use 'tar -xxxx /path/to/restore/to/', tar gives an error concerning the location being a directory, and not being able to read it. I guess I could have done 'tar -xxxx file.to.extract.to.tar' but I wasn't sure how this would behave, as far as restoring the directory structure.

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    Thanks for posting this and following up. I had a huge box of tapes from SGI systems from more than ten years ago that I was able to restore on Fedora 9 with

    mt -f /dev/st0 setblk 0
    tar -b512 -xvf /dev/st0


    Some didn't work. I got a error that it wasn't a tar archive so I used the command you posted but had to use conv=swab with a "b", not "p"


    dd bs=512 if=/dev/st0 conv=swab | tar -xvBf -


    tags: irix sgi tape restore

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