Re: [libvirt] RFC: add new API to known if domain has been updated

On Mon, Nov 15, 2010 at 10:26:22AM +0800, Osier Yang wrote: > Hi, all > > Suppose that one updated a domain, and want to restart the > domain with original configuration. > > However, currently, unless shutdown the domain first, and then > restart or reload libvirtd, otherwise domain will still be started > with changed configuration. e.g. > > # virsh list --all > Id Name State > ---------------------------------- > 1 f14 running > > # virsh dumpxml f14 | grep -A 7 cdrom > <disk type='file' device='cdrom'> > <driver name='qemu' type='raw'/> > <source file='/var/lib/libvirt/images/cd1.iso'/> > <target dev='hdc' bus='ide'/> > <readonly/> > <alias name='ide0-1-0'/> > <address type='drive' controller='0' bus='1' unit='0'/> > </disk> > > # virsh update-device f14 cd2.xml > > # virsh dumpxml f14 | grep -A 7 cdrom > <disk type='file' device='cdrom'> > <driver name='qemu' type='raw'/> > <source file='/var/lib/libvirt/images/cd2.iso'/> > <target dev='hdc' bus='ide'/> > <readonly/> > <alias name='ide0-1-0'/> > <address type='drive' controller='0' bus='1' unit='0'/> > </disk> > > # virsh destroy f14 > # virsh start f14 > > # virsh dumpxml f14 | grep -A 7 cdrom > <disk type='file' device='cdrom'> > <driver name='qemu' type='raw'/> > <source file='/var/lib/libvirt/images/cd2.iso'/> > <target dev='hdc' bus='ide'/> > <readonly/> > <alias name='ide0-1-0'/> > <address type='drive' controller='0' bus='1' unit='0'/> > </disk> > > it's caused by libvirtd doesn't known if a domain is updated or not, > it updated the domain configuration in memory, but client could > not known about it. > > As a result, one wants to start the domain with original configuration, > he has to shutdown the domain first, and then restart libvirt. This is a bug. libvirt should save a copy of the original configuration at the time the guest starts, so any live changes only remain for the duration of that boot and automatically revert at shutdown.

Regards, Daniel