CentOS - Oct 2007 - question(s) about LVM snapshots

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?

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?

Cheers,

Tony Schreiner
Biology Department
Boston College

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
volume.

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
though.
> 
> Cheers,
> 
> Tony Schreiner
> <snip sig stuff>
HTH (and that I'm correct)
--
Bill