RAID 6 corrupt/failed/otherwise not working

  • I have a 6 disk RAID 6 that is no longer working following a reboot. 3 of the disks seem to be ok, but the remaining 3 disks don't even show the correct partition type ( through 'fdisk -l') and likewise claim to have no superblocks (when trying 'mdadm --assemble'). Running blkid shows 3 disks with the correct UUID, Label, and type, but the three remaining disks with only varying PTUUIDs and a PTTYPE of 'gpt'. I've scoured Google and can't seem to find anything similar that's happened to anyone else. Using testdisk, I can see that pieces are intact, so I suspect it is recoverable, but have no idea where to begin.

    And yes, I know the first response should be "Restore from backups!" sadly, that's not an option in this case as I haven't made any in some time. (Bad sysadmin!)

    Any ideas on where I should begin? I may even be willing to pay for some assistance on this.

  • Hi,

    I have a 6 disk RAID 6

    Why using RAID / why choosing RAID6?

    so I suspect it is recoverable

    Nope, R6 with three missing disks is not recoverable ... but may be you'll get one more member running.

    but have no idea where to begin.

    List your hardware (some details about the mainboard and/or the sata-controller, and of course the HDDs used) ... then look into the log messages of your system, eventually you reveal some hints about the errors ...

    The only chance you have (before backup :P), is to recover on or more superblocks from the RAID - it is a common bug, that this superblocks are not written "physically" to the media - and getting lost during reboot (or powerloss), but this will be very difficult ...

    Did you read ? Or any other RAID-recovery-related article, which handles with more lost drives than redundancy has? (which ones?)

    Start with playing around with:
    mdadm --examine /dev/sd[...] may be you'll find some backup-superblocks ... otherwise your data is gone


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