Hi, Thanks for infos. My concern is the following : In order to establish datas exchanges between hosts and guest , I'll add a channel device to a running Guest ( as I learned from you that it's possible to do that without stopping the Guest). When the guest migrates to another host , this one must be able to retrieve the channel device parameters to be able to dialog with the migrated guest. I plan to use dumpxml to retrieve these infos. Will these infos be updated on the second host where the guest has migrated ? Thx. J.P. -----Message d'origine----- De : Michal Privoznik [mailto:mprivozn@redhat.com] Envoyé : mercredi 2 septembre 2015 14:12 À : Jean-Pierre Ribeauville; libvirt-users@redhat.com Objet : Re: [libvirt-users] about guest live migration configuration changes persistence .. On 31.08.2015 09:27, Jean-Pierre Ribeauville wrote:

Hi,

Is a change , by edit it via virsh edit , in the "local" .xml configuration file (i.e. adding a channel device) persistent when live migrating the guest on another host ?

Yes. Since the 0.9.7 release, the configuration XML is transferred to the other side too. However, by default, migrated domains are just transient (unless you pass VIR_MIGRATE_PERSIST_DEST flag, or virsh migrate --persistent ..) so the configuration XML doesn't have much effect in that case. Michal

Hi, Effectively, I use unix socket as backend. Thx for help. J.P. -----Message d'origine----- De : Michal Privoznik [mailto:mprivozn@redhat.com] Envoyé : jeudi 3 septembre 2015 11:33 À : Jean-Pierre Ribeauville; libvirt-users@redhat.com Objet : Re: [libvirt-users] about guest live migration configuration changes persistence .. On 03.09.2015 11:18, Jean-Pierre Ribeauville wrote:

Hi,

Thanks for infos.

My concern is the following :

In order to establish datas exchanges between hosts and guest , I'll add a channel device to a running Guest ( as I learned from you that it's possible to do that without stopping the Guest). When the guest migrates to another host , this one must be able to retrieve the channel device parameters to be able to dialog with the migrated guest. I plan to use dumpxml to retrieve these infos. Will these infos be updated on the second host where the guest has migrated ?

Sure. Otherwise migration would be broken in general. I mean, if guest uses say tap0 on the source, the device may already have been taken on the destination. Libvirt must then find/create another free device for the migrated domain to use, e.g. tap1. It's the same with other devices. Even consoles. But if you're using channel device (assuming you're using a unix socket as backend (=part visible within the host)), the path to the socket should be preserved. Michal