Hello,
Not sure if you are having the same issue as us, but we are following https://bugs.launchpad.net/neutron/+bug/1901707 but
are patching it with something similar to https://review.opendev.org/c/openstack/nova/+/741529 to workaround the issue until it's completely solved.
Best regards
________________________________ From: Ignazio Cassano ignaziocassano@gmail.com Sent: Wednesday, March 10, 2021 7:57:21 AM To: Sean Mooney Cc: openstack-discuss; Slawek Kaplonski Subject: Re: [stein][neutron] gratuitous arp
Hello All, please, are there news about bug 1815989 ? On stein I modified code as suggested in the patches. I am worried when I will upgrade to train: wil this bug persist ? On which openstack version this bug is resolved ? Ignazio
Il giorno mer 18 nov 2020 alle ore 07:16 Ignazio Cassano <ignaziocassano@gmail.commailto:ignaziocassano@gmail.com> ha scritto: Hello, I tried to update to last stein packages on yum and seems this bug still exists. Before the yum update I patched some files as suggested and and ping to vm worked fine. After yum update the issue returns. Please, let me know If I must patch files by hand or some new parameters in configuration can solve and/or the issue is solved in newer openstack versions. Thanks Ignazio
Il Mer 29 Apr 2020, 19:49 Sean Mooney <smooney@redhat.commailto:smooney@redhat.com> ha scritto: On Wed, 2020-04-29 at 17:10 +0200, Ignazio Cassano wrote:
Many thanks. Please keep in touch.
here are the two patches. the first https://review.opendev.org/#/c/724386/ is the actual change to add the new config opition this needs a release note and some tests but it shoudl be functional hence the [WIP] i have not enable the workaround in any job in this patch so the ci run will assert this does not break anything in the default case
the second patch is https://review.opendev.org/#/c/724387/ which enables the workaround in the multi node ci jobs and is testing that live migration exctra works when the workaround is enabled.
this should work as it is what we expect to happen if you are using a moderne nova with an old neutron. its is marked [DNM] as i dont intend that patch to merge but if the workaround is useful we migth consider enableing it for one of the jobs to get ci coverage but not all of the jobs.
i have not had time to deploy a 2 node env today but ill try and test this locally tomorow.
Ignazio
Il giorno mer 29 apr 2020 alle ore 16:55 Sean Mooney <smooney@redhat.commailto:smooney@redhat.com> ha scritto:
so bing pragmatic i think the simplest path forward given my other patches have not laned in almost 2 years is to quickly add a workaround config option to disable mulitple port bindign which we can backport and then we can try and work on the actual fix after. acording to https://bugs.launchpad.net/neutron/+bug/1815989 that shoudl serve as a workaround for thos that hav this issue but its a regression in functionality.
i can create a patch that will do that in an hour or so and submit a followup DNM patch to enabel the workaound in one of the gate jobs that tests live migration. i have a meeting in 10 mins and need to finish the pacht im currently updating but ill submit a poc once that is done.
im not sure if i will be able to spend time on the actul fix which i proposed last year but ill see what i can do.
On Wed, 2020-04-29 at 16:37 +0200, Ignazio Cassano wrote:
PS I have testing environment on queens,rocky and stein and I can make test as you need. Ignazio
Il giorno mer 29 apr 2020 alle ore 16:19 Ignazio Cassano < ignaziocassano@gmail.commailto:ignaziocassano@gmail.com> ha scritto:
Hello Sean, the following is the configuration on my compute nodes: [root@podiscsivc-kvm01 network-scripts]# rpm -qa|grep libvirt libvirt-daemon-driver-storage-iscsi-4.5.0-33.el7.x86_64 libvirt-daemon-kvm-4.5.0-33.el7.x86_64 libvirt-libs-4.5.0-33.el7.x86_64 libvirt-daemon-driver-network-4.5.0-33.el7.x86_64 libvirt-daemon-driver-nodedev-4.5.0-33.el7.x86_64 libvirt-daemon-driver-storage-gluster-4.5.0-33.el7.x86_64 libvirt-client-4.5.0-33.el7.x86_64 libvirt-daemon-driver-storage-core-4.5.0-33.el7.x86_64 libvirt-daemon-driver-storage-logical-4.5.0-33.el7.x86_64 libvirt-daemon-driver-secret-4.5.0-33.el7.x86_64 libvirt-daemon-4.5.0-33.el7.x86_64 libvirt-daemon-driver-nwfilter-4.5.0-33.el7.x86_64 libvirt-daemon-driver-storage-scsi-4.5.0-33.el7.x86_64 libvirt-daemon-driver-storage-rbd-4.5.0-33.el7.x86_64 libvirt-daemon-config-nwfilter-4.5.0-33.el7.x86_64 libvirt-daemon-driver-storage-disk-4.5.0-33.el7.x86_64 libvirt-bash-completion-4.5.0-33.el7.x86_64 libvirt-daemon-driver-qemu-4.5.0-33.el7.x86_64 libvirt-daemon-driver-storage-4.5.0-33.el7.x86_64 libvirt-python-4.5.0-1.el7.x86_64 libvirt-daemon-driver-interface-4.5.0-33.el7.x86_64 libvirt-daemon-driver-storage-mpath-4.5.0-33.el7.x86_64 [root@podiscsivc-kvm01 network-scripts]# rpm -qa|grep qemu qemu-kvm-common-ev-2.12.0-44.1.el7_8.1.x86_64 qemu-kvm-ev-2.12.0-44.1.el7_8.1.x86_64 libvirt-daemon-driver-qemu-4.5.0-33.el7.x86_64 centos-release-qemu-ev-1.0-4.el7.centos.noarch ipxe-roms-qemu-20180825-2.git133f4c.el7.noarch qemu-img-ev-2.12.0-44.1.el7_8.1.x86_64
As far as firewall driver
/etc/neutron/plugins/ml2/openvswitch_agent.ini:
firewall_driver = iptables_hybrid
I have same libvirt/qemu version on queens, on rocky and on stein
testing
environment and the same firewall driver. Live migration on provider network on queens works fine. It does not work fine on rocky and stein (vm lost connection after it
is
migrated and start to respond only when the vm send a network packet ,
for
example when chrony pools the time server).
Ignazio
Il giorno mer 29 apr 2020 alle ore 14:36 Sean Mooney <
smooney@redhat.commailto:smooney@redhat.com>
ha scritto:
On Wed, 2020-04-29 at 10:39 +0200, Ignazio Cassano wrote:
Hello, some updated about this issue. I read someone has got same issue as reported here:
https://bugs.launchpad.net/neutron/+bug/1866139
If you read the discussion, someone tells that the garp must be
sent by
qemu during live miration. If this is true, this means on rocky/stein the qemu/libvirt are
bugged.
it is not correct. qemu/libvir thas alsway used RARP which predates GARP to serve as
its mac
learning frames instead
https://en.wikipedia.org/wiki/Reverse_Address_Resolution_Protocol
https://lists.gnu.org/archive/html/qemu-devel/2009-10/msg01457.html however it looks like this was broken in 2016 in qemu 2.6.0 https://lists.gnu.org/archive/html/qemu-devel/2016-07/msg04645.html but was fixed by
https://github.com/qemu/qemu/commit/ca1ee3d6b546e841a1b9db413eb8fa09f13a061b
can you confirm you are not using the broken 2.6.0 release and are
using
2.7 or newer or 2.4 and older.
So I tried to use stein and rocky with the same version of
libvirt/qemu
packages I installed on queens (I updated compute and controllers
node
on
queens for obtaining same libvirt/qemu version deployed on rocky
and
stein).
On queens live migration on provider network continues to work
fine.
On rocky and stein not, so I think the issue is related to
openstack
components .
on queens we have only a singel prot binding and nova blindly assumes that the port binding details wont change when it does a live migration and does not update the xml for
the
netwrok interfaces.
the port binding is updated after the migration is complete in post_livemigration in rocky+ neutron optionally uses the multiple port bindings flow to prebind the port to the destiatnion so it can update the xml if needed and if post copy live migration is enable it will asyconsly activate teh dest port binding before post_livemigration shortenting the downtime.
if you are using the iptables firewall os-vif will have precreated
the
ovs port and intermediate linux bridge before the migration started which will allow neutron to wire it up (put it on
the
correct vlan and install security groups) before the vm completes the migraton.
if you are using the ovs firewall os-vif still precreates teh ovs
port
but libvirt deletes it and recreats it too. as a result there is a race when using openvswitch firewall that can result in the RARP packets being lost.
Best Regards Ignazio Cassano
Il giorno lun 27 apr 2020 alle ore 19:50 Sean Mooney <
smooney@redhat.commailto:smooney@redhat.com>
ha scritto:
> On Mon, 2020-04-27 at 18:19 +0200, Ignazio Cassano wrote: > > Hello, I have this problem with rocky or newer with
iptables_hybrid
> > firewall. > > So, can I solve using post copy live migration ??? > > so this behavior has always been how nova worked but rocky the > >
https://specs.openstack.org/openstack/nova-specs/specs/rocky/implemented/neu...
> spec intoduced teh ablity to shorten the outage by pre biding the
port and
> activating it when > the vm is resumed on the destiation host before we get to pos
live
migrate.
> > this reduces the outage time although i cant be fully elimiated
as
some
> level of packet loss is > always expected when you live migrate. > > so yes enabliy post copy live migration should help but be aware
that
if a
> network partion happens > during a post copy live migration the vm will crash and need to
be
> restarted. > it is generally safe to use and will imporve the migration
performace
but
> unlike pre copy migration if > the guess resumes on the dest and the mempry page has not been
copied
yet
> then it must wait for it to be copied > and retrive it form the souce host. if the connection too the
souce
host
> is intrupted then the vm cant > do that and the migration will fail and the instance will crash.
if
you
> are using precopy migration > if there is a network partaion during the migration the
migration will
> fail but the instance will continue > to run on the source host. > > so while i would still recommend using it, i it just good to be
aware
of
> that behavior change. > > > Thanks > > Ignazio > > > > Il Lun 27 Apr 2020, 17:57 Sean Mooney <smooney@redhat.commailto:smooney@redhat.com> ha
scritto:
> > > > > On Mon, 2020-04-27 at 17:06 +0200, Ignazio Cassano wrote: > > > > Hello, I have a problem on stein neutron. When a vm migrate
from one
> > node > > > > to another I cannot ping it for several minutes. If in the
vm I
put a
> > > > script that ping the gateway continously, the live
migration
works
> > fine > > > > > > and > > > > I can ping it. Why this happens ? I read something about
gratuitous
> > arp. > > > > > > qemu does not use gratuitous arp but instead uses an older
protocal
> > called > > > RARP > > > to do mac address learning. > > > > > > what release of openstack are you using. and are you using
iptables
> > > firewall of openvswitch firewall. > > > > > > if you are using openvswtich there is is nothing we can do
until
we
> > > finally delegate vif pluging to os-vif. > > > currently libvirt handels interface plugging for kernel ovs
when
using
> > the > > > openvswitch firewall driver > > > https://review.opendev.org/#/c/602432/ would adress that
but it
and
> > the > > > neutron patch are > > > https://review.opendev.org/#/c/640258 rather out dated.
while
libvirt
> > is > > > pluging the vif there will always be > > > a race condition where the RARP packets sent by qemu and
then mac
> > learning > > > packets will be lost. > > > > > > if you are using the iptables firewall and you have opnestack
rock or
> > > later then if you enable post copy live migration > > > it should reduce the downtime. in this conficution we do not
have
the
> > race > > > betwen neutron and libvirt so the rarp > > > packets should not be lost. > > > > > > > > > > Please, help me ? > > > > Any workaround , please ? > > > > > > > > Best Regards > > > > Ignazio > > > > > > > >