**When:** Anytime - no in use
**Prerequisites**: https://wikitech.wikimedia.org/wiki/MariaDB/Primary_switchover
**Checklist:**
NEW primary: es2039
OLD primary: es2038
[] Check configuration differences between new and old primary:
```
sudo pt-config-diff --defaults-file /root/.my.cnf h=es2038.codfw.wmnet h=es2039.codfw.wmnet
```
**Failover prep:**
[] Silence alerts on all hosts:
```
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover es7 TICKID" 'A:db-section-es7'
```
[] Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
```
sudo dbctl instance es2039 set-weight 0
sudo dbctl config commit -m "Set es2039 with weight 0 TICKID"
```
[] Topology changes, move all replicas under NEW primary
```
sudo db-switchover --read-only-master --replicating-master --timeout=25 --only-slave-move es2038 es2039
```
[] Disable puppet on both nodes
```
sudo cumin 'es2038* or es2039*' 'disable-puppet "primary switchover TICKID"'
```
[] Merge gerrit puppet change to promote NEW primary: FIXME
**Failover:**
[] Log the failover:
```
!log Starting es7 codfw failover from es2038 to es2039 - TICKID
```
[] Switch primaries:
```
sudo db-switchover --read-only-master --replicating-master --skip-slave-move es2038 es2039
echo "===== es2038 (OLD)"; sudo db-mysql es2038 -e 'show slave status\G'
echo "===== es2039 (NEW)"; sudo db-mysql es2039 -e 'show slave status\G'
```
[] Promote NEW primary in dbctl, and remove read-only
```
sudo dbctl --scope codfw section es7 set-master es2039
sudo dbctl config commit -m "Promote es2039 to es7 primary TICKID"
```
[] Clean up heartbeat table(s).
```
sudo db-mysql es2039 heartbeat -e "delete from heartbeat where file like 'es2038%';"
```
[] Restart puppet on both hosts:
```
sudo cumin 'es2038* or es2039*' 'run-puppet-agent -e "primary switchover TICKID"'
```
**Clean up tasks:**
[] change events for query killer:
```
curl -sS 'https://gerrit.wikimedia.org/r/plugins/gitiles/operations/software/+/refs/heads/master/dbtools/events_coredb_master.sql?format=TEXT' | base64 -d | sudo db-mysql es2039
curl -sS 'https://gerrit.wikimedia.org/r/plugins/gitiles/operations/software/+/refs/heads/master/dbtools/events_coredb_slave.sql?format=TEXT' | base64 -d | sudo db-mysql es2038
```
[] Update candidate primary dbctl and orchestrator notes
```
sudo dbctl instance es2038 set-candidate-master --section es7 true
sudo dbctl instance es2039 set-candidate-master --section es7 false
sudo cumin 'dborch*' 'orchestrator-client -c untag -i es2039 --tag name=candidate'
sudo cumin 'dborch*' 'orchestrator-client -c tag -i es2038 --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 db1215 zarcillo -e "select * from masters where section = 'es7';"
```
[] (If needed): Depool es2038 for maintenance.
```
sudo dbctl instance es2038 depool
sudo dbctl config commit -m "Depool es2038 TICKID"
```
[] Change es2038 weight to mimic the previous weight es2039:
```
sudo dbctl instance es2038 edit
```
[] Update/resolve this ticket.