[linux-lvm] File-system uuid on LVM snapshot

Rajesh Joseph rjoseph at redhat.com
Thu Jun 5 09:29:56 UTC 2014

Thanks Zdenek for the quick reply.

We are using thin volumes and thin snapshot, but we need all or most snapshots active. Therefore we are enabling the snapshot by-default.
As you suggested we can have a workaround to mount those snapshot volumes by using 'nouuid' option.
But the problem is in most of our use case the origin volume is mounted using the /etc/fstab. And here the mount entry is made using UUID.
So in some cases instead of Origin volume the snapshot volume get mounted.

Thanks & Regards,

----- Original Message -----
> From: "Zdenek Kabelac" <zkabelac at redhat.com>
> To: linux-lvm at redhat.com
> Sent: Thursday, June 5, 2014 2:49:51 PM
> Subject: Re: [linux-lvm] File-system uuid on LVM snapshot
> Dne 5.6.2014 10:26, Rajesh Joseph napsal(a):
> > Hi all,
> >
> > Origin volume and snapshot volume share the same file-system UUID. So after
> > the snapshot we fix the uuid by running xfs_admin or tune2fs.
> > Do you have any recommendation or best practice in this regard?
> >
> With thin pools and thin volumes - snapshot of thin volume is now created
> 'inactive' and it's skipped from default activation  (you could always
> override skip with -K  i.e. : lvchange -ay -K vg/mythinsnap)
> So with thins you should mostly have only a single volume active with the FS
> UUID.  If you happen to have multiple volumes active and you need to mount
> xfs
> filesystem  - use  'nouuid' (and eventually  norecovery for read-only
> activated snapshots)  mount options.
> For old-snapshosts - all volumes need to be available/active - so you need to
> use 'nouuid' option always.
> I don't see much point in changing  FS UUID on your snapshot - unless of
> course you plan to use snapshots as different volumes with just a 'single'
> starting point  (i.e. preinstalled tree of files)
> Regards
> Zdenek
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