Recovery of LVM Volumes on Dedicated Servers

Last modified: Friday December 1st, 2023

This article provides a guide for restoring a missing volume and the data on it when using LVM (Logical Volume Manager).

The problem/issue

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The LVM meta data of a Linux system is corrupted and the drives or partitions are not displayed when executing, PVdisplayLVdisplay or VGdisplay.

Restoring the missing volume

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  1. LVM will always make the backup of its meta data in /etc/lvm/backup/<vg_name> (VG ~ Volume Group) after a modification. Please verify this file is present and that it has all volumes and their sizes listed inside:
    logical_volumes {
    	root {
    		id = "j5rlvk-cGYE-fxbN-F8bO-p90r-x0FL-suSAUN"
    		status = ["READ", "WRITE", "VISIBLE"]
    		flags = []
    		creation_host = "unassigned-hostname"
    		creation_time = 1475126039 # 2020-05-03 10:42:51 +0530
    		segment_count = 2
    		segment1 {
    			start_extent = 0
    			extent_count = 6425 # 25.0977 Gigabytes
    			type = "striped"
    			stripe_count = 1 # linear
    			stripes = [
    				"pv0", 0
    			]
    		}
    		segment2 {
    			start_extent = 6425
    			extent_count = 15360 # 60 Gigabytes
    			type = "striped"
    			stripe_count = 1 # linear
    			stripes = [
    				"pv1", 0
    			]
    		}
    	}
    }
  2. Once you have quickly verified all the settings, save a backup of this file:
    cat /etc/lvm/backup/<vg_name> > /path/to/lvm_backup_file

    Example:

    cat /etc/lvm/backup/vg0 > /media/storage/lvm_backup_file
  3. Now reboot the server.
  4. Once you’re logged into the Rescue System, please mount the partition that contains the lvm_backup_file, copy it to the Rescue System’s filesystem, and then umount the partition:
    mount /dev/<partition> /mnt
    cp /mnt/path/to/lvm_backup_file lvm_backup_file
    umount /mnt

    Example:

    mount /dev/sdb1 /mnt
    cp /media/storage/lvm_backup_file lvm_backup_file
    umount /mnt
  5. Verify and that none of the partitions is mounted anymore:
    lsblk
  6. Output the content of the lvm_backup_file using cat, and copy the UUID (Universally Unique Identifier) of the corresponding <partition>:
    cat lvm_backup_file
    physical_volumes {
    	pv0 {
    		id = "ek9MZu-UeBK-4boe-IkJU-Q4n7-yfpX-yLK1WY" –> copy this UUID
    [...]
  7. Once you’re done, use the command below to create the Physical Volume (PV):
    pvcreate –restorefile lvm_backup_file –uuid <uuid> <partition>

    Example:

    pvcreate –restorefile lvm_backup_file –uuid ek9MZu-UeBK-4boe-IkJU-Q4n7-yfpX-yLK1WY /dev/sda1
  8. Check if the Physical Volume has been created:
    pvs
  9. Next, restore the Volume Group (VG) by using the command below:
    vgcfgrestore –force <vg_name>

    Example:

    vgcfgrestore –force vg0
  10. Sync the Volume Group data:
    vgscan
  11. Now, check if the Volume Group has been restored properly:
    vgs
  12. Next, restore the LVM:
    vgchange -ay <vg_name>

    Example:

    vgchange -ay vg0
  13. Finally, please restart the server and let it boot into the installed system. Please verify that the data is intact there.
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