hey people, thank you for XFS!
tl;dr: consider changing the kernel message "Filesystem has duplicate
UUID - can't mount" to include a hint about the existence of the nouuid
mount option. perhaps append " (use -o nouuid?)" to message?
sad backstory:
today I tried to use LVM snapshots to make consistent backups of XFS,
but I was stumped by:
mount: /mnt/snap: wrong fs type, bad option, bad superblock on /dev/mapper/vg0-test--snap, missing codepage or helper program, or other error.
dmesg(1) may have more information after failed mount system call.
and dmesg said:
XFS (dm-7): Filesystem has duplicate UUID d806fb70-8d81-4e57-a7e3-c2ed0a14af59 - can't mount
so - I thought the solution was to change the UUID of my snapshot using
`xfs_admin -U generate`. this is the response (when the snapshot is of
an active filesystem):
ERROR: The filesystem has valuable metadata changes in a log which needs to
be replayed. Mount the filesystem to replay the log, and unmount it before
re-running xfs_admin. If you are unable to mount the filesystem, then use
the xfs_repair -L option to destroy the log and attempt a repair.
Note that destroying the log may cause corruption -- please attempt a mount
of the filesystem before doing this.
so since I was unable to mount the filesystem, I tried xfs_repair -L --
which took a very long time and in the end gave me a corrupt filesystem.
... and then I found out about -o nouuid, so there was a happy ending :)
but I think it's a reasonably simple fix to give a hint to the user in
the kernel error message.
thank you!
--
venleg helsing,
Kjetil T.
