Checklist:
NEW primary: db2107
OLD primary: db2104
- Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2104.codfw.wmnet h=db2107.codfw.wmnet
Failover prep:
- Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s2 T317627" 'A:db-section-s2'
- Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db2107 set-weight 0 sudo dbctl config commit -m "Set db2107 with weight 0 T317627"
- Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db2104 db2107
- Disable puppet on both nodes
sudo cumin 'db2104* or db2107*' 'disable-puppet "primary switchover T317627"'
- Merge gerrit puppet change to promote NEW primary: https://gerrit.wikimedia.org/r/c/operations/puppet/+/831837
Failover:
- Log the failover:
!log Starting s2 codfw failover from db2104 to db2107 - T317627
- Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db2104 db2107 echo "===== db2104 (OLD)"; sudo db-mysql db2104 -e 'show slave status\G' echo "===== db2107 (NEW)"; sudo db-mysql db2107 -e 'show slave status\G'
- Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope codfw section s2 set-master db2107 sudo dbctl config commit -m "Promote db2107 to s2 codfw primary T317627"
- Restart puppet on both hosts:
sudo cumin 'db2104* or db2107*' 'run-puppet-agent -e "primary switchover T317627"'
Clean up tasks:
- Clean up heartbeat table(s).
sudo db-mysql db2107 heartbeat -e "delete from heartbeat where file like 'db2104%';"
- change events for query killer:
events_coredb_master.sql on the new primary db2107 events_coredb_slave.sql on the new slave db2104
- Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2104 set-candidate-master --section s2 true sudo dbctl instance db2107 set-candidate-master --section s2 false (dborch1001): sudo orchestrator-client -c untag -i db2107 --tag name=candidate (dborch1001): sudo orchestrator-client -c tag -i db2104 --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 = 's2';"
- (If needed): Depool db2104 for maintenance.
sudo dbctl instance db2104 depool sudo dbctl config commit -m "Depool db2104 T317627"
- Change db2104 weight to mimic the previous weight db2107:
sudo dbctl instance db2104 edit
- Update/resolve this ticket.