On Wed, May 20, 2015 at 06:11:26PM +0800, Luo Gangyi wrote: > Hi devs, > > > I find a serious problem when I try to live migrate a hybrid instance > (instance based on local disk and cinder volume attached) . > > > In current nova, such operation is allowed. > > > But I don't think libvirt can deal with such condition correctly. > > > When block migration of a hybird intance is triggered, nova will initiate > a new connection to the volume in destination compute node and then > call libvirt to do the block migration. > > However, libvirt doesn't distinguish local disk and a network volume, > it may copy both local disk and cinder volume from source to destination. > > It is dangerous to write the same volume simutaneously on source and > destination!! and apparently there is no need to do this! > > I believe we should do something to correct this, maybe patch libvirt? > or just forbid user do such operation?
Both. Nova now forbids this commit d667b6a63e80b2f8d6311c2cf224ba32628eed84 Author: Chris St. Pierre <[email protected]> Date: Wed Dec 3 16:16:34 2014 -0600 libvirt: Fail when live block migrating instance with volumes This raises an exception when attempting to live block migrate (nova live-migration --block-migrate) an instance with attached volumes. libvirt copies these volumes from themselves to themselves. At a minimum, this is horribly slow and de-sparses a sparse volume; at worst, this could cause massive data corruption. Closes-Bug: 1398999 Change-Id: Ibcd423976bb9fea46e3e1cb23cc8e5cd944d8fc2 And work is being done to allow libvirt to be told to skip cinder volumes when migrating: https://www.redhat.com/archives/libvir-list/2015-May/msg00345.html Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: [email protected]?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
