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As per the title, my mdadm RAID was in the process of migrating from level 6 to 5 when the power cut out momentarily. Unfortunately I am no longer able to reassemble the array - the assemble command outputs the following:

mdadm --assemble --force --run --verbose /dev/md0
mdadm: looking for devices for /dev/md0
mdadm: no RAID superblock on /dev/sde1
mdadm: /dev/sde1 has wrong uuid.
mdadm: no RAID superblock on /dev/sde
mdadm: /dev/sde has wrong uuid.
mdadm: no RAID superblock on /dev/sdd1
mdadm: /dev/sdd1 has wrong uuid.
mdadm: no RAID superblock on /dev/sdd
mdadm: /dev/sdd has wrong uuid.
mdadm: cannot open device /dev/sdc5: Device or resource busy
mdadm: /dev/sdc5 has wrong uuid.
mdadm: no RAID superblock on /dev/sdc2
mdadm: /dev/sdc2 has wrong uuid.
mdadm: cannot open device /dev/sdc1: Device or resource busy
mdadm: /dev/sdc1 has wrong uuid.
mdadm: cannot open device /dev/sdc: Device or resource busy
mdadm: /dev/sdc has wrong uuid.
mdadm: no RAID superblock on /dev/sda
mdadm: /dev/sda has wrong uuid.
mdadm: /dev/sdb is identified as a member of /dev/md0, slot 2.
mdadm: /dev/sda1 is identified as a member of /dev/md0, slot 3.
mdadm:/dev/md0 has an active reshape - checking if critical section needs to be restored
mdadm: Failed to find backup of critical section
mdadm: Failed to restore critical section for reshape, sorry.
      Possibly you needed to specify the --backup-file

The array was on /dev/sda1 /dev/sdb /dev/sdd1 /dev/sde1 - Is there any way to restore it?

share|improve this question
    
I've never tried this, but here's a possible solution using UUIDs from mdadm --examine /dev/sdXY output: linuxquestions.org/questions/linux-general-1/… – medigeek Oct 13 '13 at 0:02
    
Unfortunately that outputs the same "Failed to restore critical section for reshape" error. – Scott Oct 13 '13 at 0:17
1  
OK, if you didn't use a backup file while reshaping, try adding --invalid-backup to your command. It will probably set your array as read-only. You could also use overlay files to minimise the damage. You have a tutorial here: oletange.blogspot.com/2013/07/… (Use at your own risk) – medigeek Oct 13 '13 at 8:22

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