[openstack-dev] [Nova][Neutron][Live-Migration] Cross l2 agent migration and solving Nova-Neutron live migration bugs
scheuran at linux.vnet.ibm.com
Tue Jun 28 15:42:50 UTC 2016
I'm currently working on solving Nova-Neutron issues during Live
Migration. This mail is intended to raise awareness cross project and
get things kicked off.
#1 When portbinding fails, instance is migrated but stuck in error state
#2 Macvtap agent live Migration when source and target use different
physical_interface_mapping . Either the migration fails (good case)
or it would place the instance on a wrong network (worst case)
#3 (more a feature): Migration cross l2 agent not possible (e.g.
migrate from lb host to ovs host, or from ovs-hybrid to new ovsfirewall
All those problems could be solved with the same approach . The proposal
is, to bind a port to the source AND to the target port during
* Neutron would need to allow multiple bindings for a compute port and
externalize that via API.
- Neutron Spec 
- Bug  is a prereq to the spec.
* Nova would need to use those new APIs to check in pre_live_migration,
if the binding for target host is valid and to modify the instance
definition (e.g. domain.xml) during migration.
- Nova Spec 
This would solve the issues in the following way:
#1 would abort the migration before it started, so instance is still
#2 Migration is possible with all configurations
#3 would allow such a migration
Some coordination between Nova & Neutron is required. Along todays Nova
Live Migration Meeting  this will happen on the Nova midcycle. I put
an item on the agenda .
Would be great that anybody that is interested in this bugfix/feature
could comment on the specs  or  to get as much feedback as
possible before the nova midcycle in July!
 Neutron spec: https://review.openstack.org/#/c/309416
 Nova spec: https://review.openstack.org/301090
 macvtap bug: https://bugs.launchpad.net/neutron/+bug/1550400
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