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From: Paolo Bonzini <pbonzini@redhat.com>
Date: Mon, 27 Aug 2012 12:10:34 +0200
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Subject: Re: [Qemu-devel] qcow2: online snasphots : internal vs external ?
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To: qemu-devel@nongnu.org

Il 27/08/2012 11:26, Alexandre DERUMIER ha scritto:
> how can I rollback to the point of the snapshot.
> 
> exemple :
> image1.qcow2
> file : /beforesnap1
> take a snaphot (snap1), so qemu switch to snap1.qcow2
> write some file:
> file: 
>     /aftersnap1.
>     /beforesnap1
> 
> Now, how can I rollback to the point of time of snap1 ?
> I can reuse image1.qcow2, but if I write some datas on it, I don't
> see how I can return to the point of time of the snap1. (like qemu-image -a
> with internal snapshots)

If you can drop snap1.qcow2 altogether, you just use image1.qcow2 the
next time you start QEMU.

If you cannot, you create snap2.qcow2 based on image1.qcow2:

  qemu-img -f qcow2 -obacking_file=image1.qcow2 snap2.qcow2

and use it the next time you start QEMU.

Paolo