Train/SR-IOV direct port mode live-migration - question

Heib, Mohammad (Nokia - IL/Kfar Sava) goody698 at gmail.com
Wed Mar 3 12:03:44 UTC 2021


Hi All,

we recently moved to openstack Train and according to the version 
release notes the SR-IOV direct port live-migration support was added to 
this version.

so we tried to do some live-migration to vm with two SR-IOV direct ports 
attached to bond interface on the vm (no vSwitch interface or a indirect 
only direct ports) but seems that we have an issue with maintaining the 
network

connectivity during and after the live-migration, according to [1] i see 
that in order to maintain network connectivity during the migration we 
have to add one indirect or vswitch port to the bond and this interface 
will carry the

traffic during the migration and once the migration completed the direct 
port will back to be the primary slave on the target VM bond.


my question is if we don't add the indirect port we will lose the 
connectivity during the migration which makes sense to me,

but why the connectivity does not back after the migration completed 
successfully, and why the bond master boot up with no slaves on the 
target VM?

according to some documents and blueprints that I found in google 
(including [2],[3]) the guest os will receive a virtual hotplug add even 
and the

bond master will enslave those devices and connectivity will back which 
is not the case here.
so I wondering maybe I need to add some scripts to handle those events 
(if so where to add them) or some network flags to the ifcfg-* files or 
i need to use a specific guest os?


[1] : 
https://specs.openstack.org/openstack/nova-specs/specs/stein/approved/libvirt-neutron-sriov-livemigration.html 
<https://specs.openstack.org/openstack/nova-specs/specs/stein/approved/libvirt-neutron-sriov-livemigration.html>

[2] 
:https://www.researchgate.net/publication/228722278_Live_migration_with_pass-through_device_for_Linux_VM 
<https://www.researchgate.net/publication/228722278_Live_migration_with_pass-through_device_for_Linux_VM>

[3] 
:https://openstack.nimeyo.com/72653/openstack-nova-neutron-live-migration-with-direct-passthru 
<https://openstack.nimeyo.com/72653/openstack-nova-neutron-live-migration-with-direct-passthru>


*bond master ifcfg file:*

DEVICE=bond1
BONDING_OPTS=mode=active-backup
HOTPLUG=yes
TYPE=Bond
BONDING_MASTER=yes
BOOTPROTO=none
NAME=bond1
ONBOOT=yes

*slaves ifcfg files:*

TYPE=Ethernet
DEVICE=eth0
HOTPLUG=no
ONBOOT=no
MASTER=bond1
SLAVE=yes
BOOTPROTO=none
NM_CONTROLLED=no

*guest OS:*

CentOS Linux release 7.7.1908 (Core)

*
*

*/Thanks in advance for any help :)/,*



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