[libvirt] [PATCH V4] implement offline migration

[liguang]

在 2012-09-06四的 15:27 +0900，Kamezawa Hiroyuki写道：
> (2012/09/06 14:32), liguang wrote:
> > Hello, Eric & Daniel
> >
> > 在 2012-09-05三的 11:08 -0600，Eric Blake写道：
> >> On 09/05/2012 02:48 AM, Daniel P. Berrange wrote:
> >>>>>
> >>>>> I really don't like the general design of this patch, even
> >>>>> ignoring all the code bugs. I think this entire patch is
> >>>>> really just a solution in search of a problem. Offline migration
> >>>>> is already possible with existing libvirt APIs:
> >>
> >> I agree that the existing patches are making too many assumptions and
> >> not honoring flags correctly; but I'm still not sure why the user must
> >> decompose offline migration into a sequence of calls...
> >
> > yes, my original thought was to do all things together.
> >
> >>
> >>>>>
> >>>>>     domsrc = virDomainLookupByName(connsrc, "someguest");
> >>>>>     xml = virDomainGetXMLDesc(domsrc);
> >>>>>     domdst virDomainDefine(conndst, xml);
> >>>>>
> >>>>
> >>>> Um, maybe you mean offline migration is just redefinition of domain at
> >>>> target side, but what about disk images the domain used without sharing
> >>>> files between source and target, do we have to take a look at this case?
> >>>
> >>> Which can also be done already
> >>>
> >>>     virStorageVolDownload + virStorageVolUpload
> >>
> >> ...when a single virMigrate API could do the same decomposition as
> >> syntactic sugar, if the patch were cleaned up to actually obey flags.
> >> That is, why must virMigrate be a live-only operation, forcing
> >> virt-manager and all other wrappers to re-implement the same giant
> >> sequence of API calls for offline migration?
> >>
> >
> > so, libvirt may prefer APIs do one thing only?
> > maybe I have to just migrate the definition.
> >
> 
> Can you try to move the definition in an atomic way ?
> copy to the dest + delete the original with preventing other ops to the
> target vm. I hope virsh migrate can support this "move" of definition....
> 

Ok, let me try to do delete the domain configuration before migration,
I thought it's the task of passing VIR_MIGRATE_UNDEFINE_SOURCE flag to
virMigrate* APIs, but, seems too late, it occurs until migration
confirm, almost at the end.

> Thanks,
> -Kame
> 
> 

-- 
liguang    lig.fnst at cn.fujitsu.com
FNST linux kernel team