Broken RAID array ...

From: Nicolas CANIART (nicolas_at_caniart.net)
Date: 11/11/05

  • Next message: Robert Waldner: "Re: Window manager/desktop environment that's not RAM-intensive" 
    Date: Fri, 11 Nov 2005 19:47:20 +0000
To: debian-user@lists.debian.org

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    Hi all,

      It appears that for about a month my raid array is not working anymore
    (this is an evaluation after having inspected the content of each
    individual disk). I thinks it may be a bit longer. I was using raidtools
    but, as I'm under unstable, this package was removed and may not have
    been through that migration as well as I thought :(
    After some investigation i found that it does not recognize it any more
    because the two disks don't have the same UUID! as mdadm shows :

      % mdadm --examine --brief --scan --config=partitions
      ARRAY /dev/md0 level=raid1 num-devices=2 \
          UUID=b6065276:860e04ff:432f5364:f4db028c
      ARRAY /dev/md0 level=raid1 num-devices=2 \
          UUID=12e709d1:8df4e5d9:e6aa987f:b3b2318a

    As far as I can tell the disk actually used is /dev/sdb1 (sda1 content
    is outdated).
    I tried to force the array assembly but I got :

      % mdadm -A /dev/md0 --force
      md: md0 stopped.
      mdadm: /dev/sda1 has no super block - assembly aborted

    So I tried to make sda1 faulty, remove it then reinstall it; but I got :

      % mdadm --fail /dev/md0 /dev/sda1
      mdadm: cannot get array info for /dev/md0

    As far as I understand, it's because md0 is active... but I can't
    activate it; It's a dead lock !!

    To break this vicious circle, I thought I could reset sda1 UUID, but how
    can I know the one to use, or may I just rebuild the array (without
    loosing data of course !)
    Or may i use any tool to set proper super block on sda1 ?
    Is there a proper way to get myself out of that mess ?

    Thanks for your advice.
    Nicolas.

    PS : If some could explain how I get myself in that mess I would also
    greatly appreciate it ... so i won't do it again !

    - --
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