RAID 5 Missing - need help for rebuild

  • Hi,

    mdadm --assemble /dev/md127 /dev/sd[bcd] --verbose --force

    I just want to say thank you for this command!
    I modified it to keep bcd only since the a wasn't par of my RAID5.
    I don't know why but after I moved one of the 2 RAID5s I had in my machine to a new build, OMV wouldn't detect my 3 HDDs as a RAID5 anymore.
    I will keep this one in my book in case it happens to me again. :)

  • Hi everybody,

    I'm so sorry for my english (i'm french), and actually i'm panic !!!!! I'm lost my RAID5 with all my pictures, so my wife panic too.

    I wanted to add a disk to my OMV, nothing to do with RAID5.
    I stopped OMV, then I restarted.

    The first messages were "softreset failed". Maintenance or not maintenance. Ctrl + D

    OK OMV start, but i don't find my RAID5.

    I do this command "blkid"

    /dev/sdc1: UUID="bc7c4f2a-667c-47ad-9aae-7877bb724ae1" TYPE="ext4"
    /dev/sdc5: UUID="ed3b823d-6149-4a1e-beeb-ba0885771be1" TYPE="swap"
    /dev/sda: UUID="f7093f38-a653-0b7f-2f4b-306f818ce6cf" LABEL="NAS:raid5" TYPE="linux_raid_member" UUID_SUB="5a0d1f21-4ca4-789f-08e7-1964e635b935"
    /dev/sdb: UUID="f7093f38-a653-0b7f-2f4b-306f818ce6cf" LABEL="NAS:raid5" TYPE="linux_raid_member" UUID_SUB="d12f04d9-f580-d30c-8395-9f693ee17b19"
    /dev/sde: UUID="f7093f38-a653-0b7f-2f4b-306f818ce6cf" LABEL="NAS:raid5" TYPE="linux_raid_member" UUID_SUB="24e72a99-3c5b-f0e5-76c1-218999a4d3d3"
    /dev/sdd1: LABEL="DD1500" UUID="40cfb129-6726-4146-8eb4-201f517c3918" TYPE="ext4 "

    and this "cat /proc/mdstat"

    Personalities : [raid6] [raid5] [raid4]
    md126 : inactive sdb[1](S)
    1953513560 blocks super 1.2
    md127 : inactive sda[0] sde[2]
    3907027120 blocks super 1.2
    unused devices: <none>

    I do this command " mdadm --assemble /dev/md127 /dev/sd[abe] --verbose --force"

    mdadm: looking for devices for /dev/md127
    mdadm: /dev/sda is busy - skipping
    mdadm: /dev/sdb is busy - skipping
    mdadm: /dev/sde is busy - skipping

    But it does work...
    Please help me

  • i find to stop md126 and md127

    root@NAS:~# mdadm --stop /dev/md126
    mdadm: stopped /dev/md126
    root@NAS:~# mdadm --stop /dev/md127
    mdadm: stopped /dev/md127

    and i try to assemble this

    but just 2 disks is in my raid. I don't find the good write ....

  • After stopping, you need to include all three drives.

    Remember raid is not backup...

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  • Stop md126 and md127 as you did above.
    Include all 3 drives as you tried first:

    mdadm --assemble /dev/md127 /dev/sd[abe] --verbose --force

    Your last step was wrong, you assembled only 2 drives into md127 and 1 in md126.

  • thinks a lot for your answers but it does not work

  • As far as i understand your Raid5 should be online. Just with 2 drives, but it should be online.
    Check your OMV-Gui for the Raid and get a backup of your data.

    Maybe you should wait for more competent answers from ryecoaaron or any other professional.

  • Hi,

    i read this thread, but i cannot understand, why your RAID5 was breaking up - one drive was sorted out for /dev/md126, the other two drives stood on md127 ... and originally all three should be on md0 :P

    But anyway, you have to:
    - remove the drive from md126
    should be [sudo] mdadm /dev/md126 --remove /dev/sde (sudo only if ya are not root ...)

    - adding that drive as hotspare to md127 (starts the rebuild immediately)
    should be [sudo] mdadm /dev/md127 --add /dev/sde

    Working backup is always necessary!Beg and hope, that no more drive will fail while rebuilding ...


  • Same issue here.

    omv runs as a vm in a proxmox node.
    has 4x4T disks passed-through from the node and a raid5 on them.

    suddenly after a reboot I can't see no raid, the disks and the filesystem is still there in the list but refered to as missing

    /proc/mdstat shows no raid.

    root@omvbackup:~/# mdadm --assemble /dev/md127 /dev/vd[abcd] --verbose --force
    mdadm: looking for devices for /dev/md127
    mdadm: Cannot assemble mbr metadata on /dev/vda
    mdadm: /dev/vda has no superblock - assembly aborted

    Then I go to raid management, recreate the raid from scratch with same disks and name, and voila... the filesystem is intact with all the data there...

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