Checklist:
NEW primary: db2114
OLD primary: db2129
- Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2129.codfw.wmnet h=db2114.codfw.wmnet
Failover prep:
- Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary codfw s6 T317850" 'A:db-section-s6'
- Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db2114 set-weight 0 sudo dbctl config commit -m "Set db2114 with weight 0 T317850"
- Topology changes, move all replicas under NEW primary
sudo db-switchover --replicating-master --read-only-master --timeout=25 --only-slave-move db2129 db2114
- Disable puppet on both nodes
sudo cumin 'db2129* or db2114*' 'disable-puppet "primary switchover T317850"'
- Merge gerrit puppet change to promote NEW primary: https://gerrit.wikimedia.org/r/c/operations/puppet/+/832448
Failover:
- Log the failover:
!log Starting s6 codfw failover from db2129 to db2114 - T317850
- Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db2129 db2114 echo "===== db2129 (OLD)"; sudo db-mysql db2129 -e 'show slave status\G' echo "===== db2114 (NEW)"; sudo db-mysql db2114 -e 'show slave status\G'
- Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope codfw section s6 set-master db2114 sudo dbctl config commit -m "Promote db2114 to s6 codfw master T317850"
- Restart puppet on both hosts:
sudo cumin 'db2129* or db2114*' 'run-puppet-agent -e "primary switchover T317850"'
Clean up tasks:
- Clean up heartbeat table(s).
sudo db-mysql db2114 heartbeat -e "delete from heartbeat where file like 'db2129%';"
- change events for query killer:
events_coredb_master.sql on the new primary db2114 events_coredb_slave.sql on the new slave db2129
- Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2129 set-candidate-master --section s6 true sudo dbctl instance db2114 set-candidate-master --section s6 false (dborch1001): sudo orchestrator-client -c untag -i db2114 --tag name=candidate (dborch1001): sudo orchestrator-client -c tag -i db2129 --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 = 's6';"
- (If needed): Depool db2129 for maintenance.
sudo dbctl instance db2129 depool sudo dbctl config commit -m "Depool db2129 T317850"
- Change db2129 weight to mimic the previous weight db2114:
sudo dbctl instance db2129 edit
- Update/resolve this ticket.