[CentOS] question(s) about LVM snapshots

William L. Maltby CentOS4Bill at triad.rr.com
Thu Oct 11 23:16:49 UTC 2007

On Thu, 2007-10-11 at 15:47 -0400, Tony Schreiner wrote:
> I've recently begun to try out LVM snapshots and I have 2 things I'm  
> wondering about
> My intention is to run backups off the snapshot. As a first  
> iteration, I left 15% of the disk for the snapshot LV.
> 1.
> The HOWTO instructions suggest that the snapshot is in effect as long  
> as the snapshot LV exists, and use lvremove to disable the snapshot.   
> Is this the proper way?

I reviewd some code I wrote and tested during 8/06 and I did not remove
the logical volume. I just unmounted it. ISTR that my reading of stuff
at that time did *not* require the snapshot volume be removed.

> 2.
> I chose 15% because the disk  is not that active and I think it will  
> be plenty for the duration of the backup I'm doing. Is there a way to  
> track how much space the snapshot is actually using?

My code seems to indicate that once the snapshot voluke is mounted, the
usual "df <options of your choice>" work just as on any other logical

BTW, this *may* have been LVM 1? Not sure now and haven't researched
since. But it did work great and the snapshot volume (IIRC) retains its
contents. This, I'm sure can be useful. Haven't really though about it

> Cheers,
> Tony Schreiner
> <snip sig stuff>

HTH (and that I'm correct)

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