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.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.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.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/neutron-new-port-binding-api.html
> > > > > 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.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
> > > > > > >
> > > > > > >
> > > > >
> > > > >
> > >
> > >