XFS Filesystem has duplicate UUID

Part of my backup strategy includes cloned disks. The idea is in case of abrupt failure of an internal disk the clone disk restores usage continuity in a few minutes. I have had disks fail abruptly. Hence my motivation.

The cloned disks are updated every three to four days. With the cloned disk alone, the maximum loss of changed data is the same period. Hourly backups are used to restore modified files from within that period.

I wanted to connect one of the cloned disks to check the file date stamp of a single file. If the file date stamp was the same I would have to use my weekly backups to restore the file.

On one of the disks is an xfs partition. When I connected the cloned disk and attempted to manually mount the xfs partition, I saw the following message:

XFS (sde8): Filesystem has duplicate UUID 467fe84f-a6b0-4e91-94ce-c97af6aeeb09 - can't mount

Puzzled for a few moments, I remembered I had the same problem when I wrote my shell script that clones the disks.

The message is a result of the internal disk and the cloned disk having two xfs partitions with the same UUID. This makes sense because cloning matches all partition attributes. xfs is designed not to like mounting partitions with the same UUID.

Had I connected the cloned disk in a different system I would not have seen the message.

The solution is straightforward. Use the nouuid mount option. That option informs xfs to ignore UUIDs. For example:

mount -t xfs /dev/sde8 /mnt/backups -o ro,nouuid

Posted: January 16, 2020 Category: Usability Tagged: General

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