Re: [linux-lvm] xfs_freeze & lvm2

[Klaus Strebel <klaus.strebel@gmx.net>]

Rich schrieb:
> i am not subscribed, so i would be thankful if i could get a reply with 
> cc. thanks.
> 
> i tried making snapshots of xfs filesystem on lvm2. if xfs was frozen, 
> lvcreate stopped at
> 
>     Suspending space-data
>          dm suspend space-data  N
> 
> issuing xfs_freeze -u allowed the process to continue.
> in this list, Thu, 09 Jun 2005 Klaus Strebel wrote :
> 
> "with LVM2 the XFS filesystem is 'frozen' automaticly on the mount 
> -onouuid,ro ( not quite sure, but probably also for LVM1 ..., think it's 
> in the XFS code ).
> So, forget xfs_freeze."
> 
> as i understand it, consistent copy is created when lvcreate is issued, 
> not when snapshot volume is mounted - is this right ?
As i understood things, no. Mounttime matters ;-) see 
<http://www.tldp.org/HOWTO/LVM-HOWTO/snapshotintro.html> and as example 
<http://www.tldp.org/HOWTO/LVM-HOWTO/snapshots_backup.html>.

> if so, shouldn't filesystem also be frozen when a snapshot volume is 
> created ?
... see above ...
> if it actually is done together with snapshot, does this mean that i 
> really can forget about xfs_freeze and just create snapshots ?
> must i specify ro in mount options or is this optional ?
Well, if i'm wrong ( and to be honest, i didn't play around with all the 
stuff for 1 1/2 years now :-( ) somebody might correct me, but if i 
remember postings from linux-xfs mailing list, rw-snapshots with XFS is 
not quite unstable ...

Cheers
Klaus

-- 

Klaus Strebel, Dipl.-Inform. (FH), mailto:klaus.strebel@gmx.net

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