You'll need to use ovs 2.17 (at least python-ovs 2.17) to use raft effectively. Leader transfer on compaction will cause disconnected clients, and before python-ovs 2.17, monitor-cond-since/update3 support was not there to make the reconnect happen using a snapshot instead of a full dump of the db from ovsdb-server.
Terry On Wed, Aug 3, 2022 at 10:44 AM Oleksandr Mykhalskyi via discuss <ovs-discuss@openvswitch.org> wrote: > > Dear openvswitch developers, > > > > After recent update of our openstack wallaby cloud, when OVS was updated from > 2.15.0 to 2.15.2, we observe new OVS DB behavior with often (every 10-20 min) > transferring leadership in raft cluster. > > Transferring leadership was implemented by > https://patchwork.ozlabs.org/project/openvswitch/patch/20210506124731.3599531-1-i.maxim...@ovn.org/#2682913 > > It caused a lot of errors in our cloud, with neutron <-> OVN interaction. > > > > First of all, we have to schedule regular (every 10min) manual compaction to > avoid transferring leadership, which is unnecessary for us. > > Then, we tried to find out, why OVN database triggers compacting so often and > we can see next things: > > > > 1) After restart of all OVN SB DB instances in raft cluster, there is no > compaction for about 20-24 hours; > > > > 2) First time, compaction starts after 24 hours, or earlier after > doubling of DB size (after restart, DB size was 105MB, compaction was > triggered after DB size ~ 210MB); > > > > 3) After this first compaction, we have next compactions every 10-20 > min. But it’s unclear why? > > In http://www.openvswitch.org/support/dist-docs/ovsdb-server.1.txt we have > next description - “A database is also compacted automatically when a > transaction is logged if it is over 2 times as large as its previous > compacted size (and at least 10 MB)”. > > But according our usual activity (below), SB DB should not trigger > compaction every 10-20 min, because during 10 min we have DB growth ~ 1Mb > only: > > > > Wed 03 Aug 2022 07:50:14 AM EDT > > > > # ls -l /var/lib/docker/volumes/ovn_sb_db/_data/ovnsb.db > > -rw-r----- 1 root root 105226017 Aug 3 07:50 > /var/lib/docker/volumes/ovn_sb_db/_data/ovnsb.db > > > > # docker exec ovn_sb_db ovs-appctl -t /var/run/ovn/ovnsb_db.ctl memory/show > > cells:2422190 monitors:8 raft-connections:4 raft-log:2 sessions:88 > > > > # docker exec ovn_sb_db ovsdb-tool show-log > /var/lib/openvswitch/ovn-sb/ovnsb.db | grep -c record > > 6 > > > > Wed 03 Aug 2022 07:59:39 AM EDT > > > > # ls -l /var/lib/docker/volumes/ovn_sb_db/_data/ovnsb.db > > -rw-r----- 1 root root 106027676 Aug 3 07:59 > /var/lib/docker/volumes/ovn_sb_db/_data/ovnsb.db > > > > docker exec ovn_sb_db ovs-appctl -t /var/run/ovn/ovnsb_db.ctl memory/show > > cells:2422190 monitors:8 raft-connections:4 raft-log:1925 sessions:88 > > > > # docker exec ovn_sb_db ovsdb-tool show-log > /var/lib/openvswitch/ovn-sb/ovnsb.db | grep -c record > > 3852 > > > > 4) After investigation of old logs, we realized that we had often > compaction in OVS 2.15.0 also, for a long time, according regular messages > like “Unreasonably long 2939ms poll interval” (every 10-20 min). We just > didn`t see impact/errors from this compaction, like with patch “transferring > leadership”. > > > > > > Could you please help to find out – is it some bug with compaction trigger or > expected behaviour? > > > > P.S. It would be good to have a choice in OVSDB – do we want to use > transferring leadership or no. > > > > Thank you. > > > > > > Oleksandr Mykhalskyi, System Engineer > Netcracker Technology > > > > > > > ________________________________ > The information transmitted herein is intended only for the person or entity > to which it is addressed and may contain confidential, proprietary and/or > privileged material. Any review, retransmission, dissemination or other use > of, or taking of any action in reliance upon, this information by persons or > entities other than the intended recipient is prohibited. If you received > this in error, please contact the sender and delete the material from any > computer. > > _______________________________________________ > discuss mailing list > disc...@openvswitch.org > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss _______________________________________________ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
