Unable to mount the filesystem due to duplicate UUID error.

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • XFS

Issue

  • Unable to mount the XFS filesystem. Duplicate UUID errors are logged in dmesg:

    # dmesg | tail
Oct 16 03:29:22 hostname kernel: XFS (sdc1): Filesystem has duplicate UUID c4e2eef9-c744-4c64-8ebc-044373f84ddc - can't mount
Oct 16 03:29:27 hostname kernel: XFS (sdc1): Filesystem has duplicate UUID c4e2eef9-c744-4c64-8ebc-044373f84ddc - can't mount

  • How to change UUID of the XFS filesystem?

  • Unable to mount LVM snapshot of a XFS file-system:

    # mount /dev/xfs_snap/snap /snap
mount: wrong fs type, bad option, bad superblock on /dev/xfs_snap/snap,
   missing codepage or other error
   In some cases useful info is found in syslog - try
   dmesg | tail  or so

Resolution

  • Generate unique and new UUID for the affected XFS filesystem using xfs_admin utility:

    #  xfs_admin -U generate </path/to/dev/device>
Clearing log and setting UUID
writing all SBs
new UUID = 9e1c84e4-b33f-4138-9992-c38b25b84237

  • It is possible to specify custom UUID using the xfs_admin utility, as well:

    # xfs_admin -U 9e1c84e4-b33f-4138-9992-c38b25b84237 </path/to/dev/device>

  • If the UUID of boot or root partition is changed, rebuilding the grub is required:

    # grub2-mkconfig -o /boot/grub2/grub.cfg

    On UEFI-based machines, enter:

    # grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

  • As a workaround, mount the filesystem with the nouuid option:

    # mount -o nouuid </path/to/dev/device> </path/to/mount/point>

  • Please refer to article for changing UUID of ext* filesystem.

Root Cause

  • XFS filesystem has UUID, which are unique identifiers of the filesystem.
    Two file systems with same UUID can not be mounted on the same system.

  • If the backing storage of filesystem is cloned or replicated, the metadata that contains UUID information for filesystem will be identical on both filesystems.

  • LVM snapshots will have same UUID as original filesystem.

Diagnostic Steps

  • Check /var/log/messages or journal or dmesg while mounting the filesystem:

    #  tail -f /var/log/messages
Oct 16 03:29:22 hostname kernel: XFS (sdc1): Filesystem has duplicate UUID c4e2eef9-c744-4c64-8ebc-044373f84ddc - can't mount
Oct 16 03:29:27 hostname kernel: XFS (sdc1): Filesystem has duplicate UUID c4e2eef9-c744-4c64-8ebc-044373f84ddc - can't mount

  • Mount the filesystem using nouuid option to check integrity of the filesystem:

    # mount -o nouuid </path/to/dev/device> </path/to/mount/point>

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