Re: Best choice for copy/clone/snapshot

[Ross Boylan <ross@biostat.ucsf.edu>]

Thanks for all the info.  I have one follow up.
On Wed, 2009-05-13 at 10:07 +0300, Avi Kivity wrote:
> 
> > As I install software onto a system I want to preserve its
> state--just
> > the disk state---at various points so I can go back.  What is the
> best
> > way to do this?
> >   
> 
> LVM snapshots.  Read up on the 'lvcreate -s' command and option.
I may have been unclear.  I meant as I install software on the VM.
Since some of them are running Windows, they can't do LVM.  I am running
LVM on my host Linux system.

Or are you suggesting that I put the image files on a snapshottable
partition?  Over time the snapshot seems likely to accumulate a lot of
original sectors that don't involve the disk image I care about.

Or do you mean I should back each virtual disk with an LVM volume?  That
does seem cleaner; I've just been following the docs and they use
regular files.  They say I can't just use a raw partition, but maybe
kvm-img -f qcow2 /dev/MyVolumeGroup/Volume10 ?
Does that give better performance?  The one drawback I see is that I'd
have to really take the space I wanted, rather than having it only
notionally reserved for a file.  I'm not sure how growing the logical
volume would interact with qcow...

Ross