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sBlatt
Asked: 2010-11-20 01:47:17 +0800 CST

recover LVM after hdd crash

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Yesterday, one hdd of my LVM crashed (smart-error)

The Machine has the following setup:
- 4 hdds
- 1 Partition Raid10 (System, 4*50GB)
- 1 Partition normal (/boot, 200MB, sda)
- 1 Partition LVM2 (Data, 4*~850GB)
- Ubuntu 10.04 Server (headless)

Now my lvm won't mount anymore, Ubuntu asks me to skip or manually recover on bootup. When I press S the system starts, but without my lvm getting mounted.

Now my system partition does not seam to be affected (/proc/mdstat looks as usual) an /boot works fine, too.

What I will try now is to
- buy a new hdd
- Integrate the hdd in my lvm
- Try to remove the sda-part of the lvm (copy it over to the new sde, or whatever lvm wants)
- Do the raid stuff (I think I'll find out how to do that, otherwise I'll ask a separate question)

Now my problems:
- How can I remove sda from the lvm (remove meaning copy contents and mark partition as not in use so I can unplug the drive)?
- If I am not able to remove the partition normally, are there any tools to recover the files on this partition, so I could manually copy them to the "new" lvm?

Thank you for your help

EDIT:
separated solution from Question

filesystem hardware data-recovery lvm

3 Answers

  1. thinking pvmove is the command-line you are looking for...details here: http://tldp.org/HOWTO/LVM-HOWTO/removeadisk.html

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  2. It's not too clear to me whether your LVM is on top of RAID or not? If not then you're flat out of luck getting any data off of the LVM.

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  3. Best Answer

    Computer works now. Here my detailed steps:
    My sda (faulty drive) partitions looked like this:
    sda1: /boot
    sda2: raid10 member (system)
    sda3: lvm member

    • Attach new replacement hdd
    • dd if=/dev/sda of=/dev/sde (copy the cotents of the faulty hdd to the new one, actually I did ctrl+c after a minute as I only needed the partition table)
    • dd if=/dev/sda1 of=/dev/sde1 (copy /boot partition to the new disk)
    • vgextend my_volume_group /dev/sde3 (add the lvm partition of the new disk to my lvm)
    • pvmove /dev/sda3 (move the data of the faulty drive to another drive)
    • Remove sda2 from my raid10
    • changed fstab to get /boot from sda1 not by uuid (as this changes when replacing hdd)
    • grub-install /dev/sde (as it's an upgraded version from 8.04, newer versions would need grub2-install)

    now my sde partitions lokked the follow:
    sde1: /boot
    sde2: raid partition (not initialized)
    sde3: lvm partition (initialized, lvm worked again)

    I shutdown the computer, replaced the harddisk (so sde would be sda, removed old sda) and reboot
    EVERYTHING worked! I did not even have to use a live cd to fix bootloader/other stuff, miraculously sda2 was recognised as raid10 member and was automatically initialized!

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