[libvirt-users] blockcopy for libvirt and version compatibility

[Mark Trinh]

Thanks Eric!  This was exactly what I was looking for.


On Fri, Dec 20, 2013 at 11:48 AM, Eric Blake <eblake at redhat.com> wrote:

> On 12/20/2013 11:45 AM, Mark Trinh wrote:
> > I'm currently running:
> > virsh --version
> > 1.0.2
> >
> > libvirtd --version
> > libvirtd (libvirt) 1.0.2
> >
> > I have a couple questions.
> >
> > 1. Can I upgrade my libvirt.so version to use with an older libvirtd?  In
> > other words, does the versions of libvirt and libvirtd need to be in lock
> > step?
>
> No, they do not have to be in lockstep.  libvirt.so communicates to a
> local libvirtd the same way it communicates to a remote machine, and we
> took great care in the design to ensure that things error out nicely if
> the libvirt.so client is newer than the remote server; conversely, if
> the client is older, the changes have always been back-compat so that a
> newer server will always talk to the client correctly (although the
> client being older means that you can't take full advantage of the server).
>
> >
> >
> > 2. I'm able to use virsh blockcopy, but I want to do it programmatically
> > via C.  I looked through the API and was not able to see any references
> to
> > that.  I did see mention of virDomainBlockCopy on the TIP of the git
> > repository, but no other references to it.
>
> The source code to virsh shows the APIs that we used; this is a good
> starting point for any other C binding, and also for any other language
> binding if you can map the C bindings over to your language bindings.
> In particular, tools/virsh-domain.c:cmdBlockCopy() is currently
> implemented atop the virDomainBlockRebase() API call with the
> VIR_DOMAIN_BLOCK_REBASE_COPY flag (but the door is open to also
> implement it atop a newer more-powerful virDomainBlockCopy() once we
> start targetting some of qemu 1.7 or 2.0's newer features).
>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
>
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