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Thread: Need help with LVM recovery

  1. #1
    Join Date
    May 2008

    Need help with LVM recovery


    I need some information on how LVM works. To start off let me explain my situation.
    I had an older redhat system that was storing some old archive backups. The system consisted out of two drives in a LVM2 Volume set.

    The first disk had 2 partitions.

    Device Boot Start End Blocks Id System
    /dev/sdc1 * 63 208844 104391 83 Linux
    (100mb Boot Partition)
    Partition 1 does not start on physical sector boundary.
    /dev/sdc2 208845 2930272064 1465031610 8e Linux LVM
    Partition 2 does not start on physical sector boundary.

    The second disk had only 1 LVM partition

    For some reason something when wrong with the ext3 filesystem and the system stopped booting.
    I suspect that one of the drives are slightly dodgy. As it turns out this was only discovered once we realized we need some of the data off the old backups. To be belt and braces I thought it best to rather clone both disk to new disk before I attempt a recover as I'm no Linux Expert and would probably need a few goes at it.

    And this is where I stuffed things up badly for myself.

    To clone the disks I connected them to my ubuntu system with two new 2TB disks. I installed ddrescue. But when I started my first clone I made a mistake in identifying which drive is which.

    I ended up coping 800Mb (821 515 KB ) of the first disk over the beginning of the second disk. Before this happened I was able to see the VolumeGroup in ubuntu but of course after a reboot the system now thinks that disk one and disk two are the same disk even though only the beginning of the drives have been overwritten.

    How do I now go about recovering my LVM.
    For now I've disconnected disk one and only connected disk 2 (the overwritten disk) running a pvscan yields the following

    Found duplicate PV x1Yg3zsd2YJAzjo22vTs02S9jAbaj1mX: using /dev/sdc2
    Couldn't find device with uuid p8yKhC-7t70-kSti-Cz7A-WznH-94lZ-Aj6GAp.
    PV unknown device VG VolGroup00 lvm2 [1,36 TiB / 0 free]
    PV /dev/sdc2 VG VolGroup00 lvm2 [1,36 TiB / 0 free]
    Total: 2 [2,73 TiB] / in use: 2 [2,73 TiB] / in no VG: 0 [0 ]

    Any guidance in how to reassemble this would be appreciated.

    Thank You

  2. #2
    Join Date
    Sep 2011
    Behind you!
    Ubuntu 12.04 Precise Pangolin

    Re: Need help with LVM recovery

    Quote Originally Posted by netwise View Post
    I need some information on how LVM works.
    I don't have time to go through you post fully (need to leave work) but I have how-to documentation on how to setup LVM, backup and restore in my signature link (setup ubuntu)

    I hope it helps clarify LVM for you.


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