Re: [Qemu-devel] Fwd: Fwd: [Qemu-discuss] wrong command on snapshot wiki

[Eric Blake <eblake@redhat.com>]

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On 01/25/2015 04:17 PM, vrms@netcologne.de wrote:
> I am not 100% sure whether this is the right place to raise this issue.
> Maybe you can forward this to right person
> |
> I have the feeling this wikipage >>>
> http://wiki.qemu.org/Documentation/CreateSnapshot is wrong. I think the
> decription and the posted command for creating snapshots [||qemu-img
> create -f qcow2 -b centos-cleaninstall.img snapshot.img|] |is actually
> describing copy-on-write (or overlay) images. And I think this is not
> the same thing

That is the procedure for creating external snapshots (the original file
is the snapshot, and the newly created overlay stores the delta).

> 
> |||As far as I know such a command would creat a copy-on-write image and
> not a snapshot|. On the german debianforum.de I got another suggestion
> to vreate snaptshots which I have not tested yet, but sounds more likely
> to be correct to me
> 
>     qemu-img snapshot -c [snapshot_name] [base_name]

That is the procedure fore creating internal snapshots (a single file
holds both the snapshot and all changes since the snapshot).

Both methods have their benefits and drawbacks, but right now, there is
more work being done with external snapshots than with internal snapshots.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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