SHA256 SUM doesn't match

Discussion in 'all things UNIX' started by amarildojr, Dec 8, 2015.

  1. amarildojr

    amarildojr Registered Member

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    I've got a weird situation going on.

    I had an old Arch DVD and it's SHA1SUM checked fine with the one on the Arch website, so I used it to re-install the system. Then I grabbed my 2 DVD+RW's I have and erased them completely. Both DVD's are equal, both are from the same brand (Sony) and bought the same day from the same store. I used the first DVD to burn the newst Arch ISO, and the SHA1SUM checked fine. Then I burned openSUSE Leap 42.1 on the second DVD, and now the SHA256SUM doesn't check. I tried K3B and xfburn, tried quick and long erases, tried even installing openSUSE before burning the DVD, and nothing. It's interesting because the SHA256SUM on my /home folder checks with the real SUM, and K3B tells me the correct MD5 before burning.... but after burning nothing checks out.

    Does anyone have an idea of what it could be? I'll try burning Arch on the 2nd DVD to see if it is the problem.
     
  2. Adric

    Adric Registered Member

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    This thread may shed some light as to a possibility. I had a similar problem and solved it using -type DVDs instead of +type
     
    Last edited: Dec 8, 2015
  3. amarildojr

    amarildojr Registered Member

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    Uhhh..... I just realized I'm using DVD-RW. Sorry.
     
  4. Adric

    Adric Registered Member

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    The extra padding at the end can also happen with certain burners as stated in the thread. Using -R(W) will minimize the chances, but you can still end up with the padding depending on which burner you have. In my case, it made a difference with the burner I was using. I would suggest reading the whole thread to get a better idea of what is happening.
     
  5. Palancar

    Palancar Registered Member

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    Late to the party again! I generally like to do the sha256sum on the file before writing it to the optical media. It eliminates the + - discussion and I have never had a bad write when I know I started with a solid file initially. It also saves time spinning out a bad file and trashing a disc.

    Good burning software will auto verify during the spin anyway, but it will only verify to match the file you send out. That is why I like to verify the file pre-send!


    ps - I know you verified before you sent too. I guess my point was if the file is correct and the burn verifies to the file it must be correct, right? I have never seen what you described but I always use the same optical media. Maybe that is why.
     
  6. amarildojr

    amarildojr Registered Member

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    I think it might be the media.

    DVD-RW 1 had Arch and SHA1SUM checked fine.
    DVD-RW 2 used to work fine, but now it doesn't matter which burner it's burned, it will fail checksums.

    I then took DVD-RW 1, did a full erase, and burned Debian's mini.iso onto it. Sums checked fine.

    I'll test Debian today. Arch is behaving weirdly, my HD is burning hot and my memory usage, which was 8% two months ago, is now on 50% at idle.

    Code:
    [amarildo@amarildo ~]$ sha256sum /dev/cdrom
    2441421205fd8f3772be6032d51f5cc16726f72d5c5839894dffa0a6eecdbb9f  /dev/cdrom

    ftp://ftp.debian.org/debian/dists/jessie/main/installer-amd64/current/images/SHA256SUMS
     
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