Affected wikis:: x2
Checklist:
NEW primary: db2144
OLD primary: db2142
- Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2142.codfw.wmnet h=db2144.codfw.wmnet
Failover prep:
- Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover x2 T328001" 'A:db-section-x2'
- Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db2144 set-weight 0 sudo dbctl config commit -m "Set db2144 with weight 0 T328001"
- Topology changes, move all replicas under NEW primary
This didn't work and I had to use orchestrator: sudo db-switchover --replicating-master --timeout=25 --only-slave-move db2142 db2144
- Disable puppet on both nodes
sudo cumin 'db2142* or db2144*' 'disable-puppet "primary switchover T328001"'
- Merge gerrit puppet change to promote NEW primary: https://gerrit.wikimedia.org/r/c/operations/puppet/+/883836/
Failover:
- Log the failover:
!log Starting x2 codfw failover from db2142 to db2144 - T328001
- Switch primaries:
sudo db-switchover --replicating-master --skip-slave-move db2142 db2144 echo "===== db2142 (OLD)"; sudo db-mysql db2142 -e 'show slave status\G' echo "===== db2144 (NEW)"; sudo db-mysql db2144 -e 'show slave status\G'
- Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope codfw section x2 set-master db2144 sudo dbctl config commit -m "Promote db2144 to x2 primary T313811"
- Restart puppet on both hosts:
sudo cumin 'db2142* or db2144*' 'run-puppet-agent -e "primary switchover T328001"'
Clean up tasks:
- Clean up heartbeat table(s).
sudo db-mysql db2144 heartbeat -e "delete from heartbeat where file like 'db2142%';" sudo db-mysql db1151 heartbeat -e "delete from heartbeat where file like 'db2142%';"
- change events for query killer:
events_coredb_master.sql on the new primary db2144 events_coredb_slave.sql on the new slave db2142
- Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2142 set-candidate-master --section x2 true sudo dbctl instance db2144 set-candidate-master --section x2 false (dborch1001): sudo orchestrator-client -c untag -i db2144 --tag name=candidate (dborch1001): sudo orchestrator-client -c tag -i db2142 --tag name=candidate
- Check zarcillo was updated
- db-switchover should do this. If it fails, do it manually: https://phabricator.wikimedia.org/P13956
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 'x2';"
- Change db2142 weight to mimic the previous weight db2144:
sudo dbctl instance db2142 edit
- Update/resolve this ticket.