**When:** Thursday 30th June at 06:00 AM UTC
** Prerequisites **: https://wikitech.wikimedia.org/wiki/MariaDB/Primary_switchover
[x] Team calendar invite
**Affected wikis:**:
The x1 cluster is used by MediaWiki at WMF for databases that are "global" or "cross-wiki" in nature, and are typically associated with a MediaWiki extension
Affected features:
```
BounceHandler
Cognate
ContentTranslation
Echo
Flow
GrowthExperiments
ReadingLists
UrlShortener
WikimediaEditorTasks
```
**Checklist:**
NEW primary: db1120
OLD primary: db1103
[x] Check configuration differences between new and old primary:
```
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1103.eqiad.wmnet h=db1120.eqiad.wmnet
```
**Failover prep:**
[x] Silence alerts on all hosts:
```
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover x1 T300472" 'A:db-section-x1'
```
[x] Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
```
sudo dbctl instance db1120 set-weight 0
sudo dbctl config commit -m "Set db1120 with weight 0 T300472"
```
[x] Topology changes, move all replicas under NEW primary
```
sudo db-switchover --timeout=25 --only-slave-move db1103 db1120
```
[x] Disable puppet on both nodes
```
sudo cumin 'db1103* or db1120*' 'disable-puppet "primary switchover T300472"'
```
[x] Merge gerrit puppet change to promote NEW primary: https://gerrit.wikimedia.org/r/c/operations/puppet/+/809607
**Failover:**
[x] Log the failover:
```
!log Starting x1 eqiad failover from db1103 to db1120 - T300472
```
[x] Switch primaries:
```
db-mysql db1103 -e "set global read_only=1"
sudo db-switchover --read-only-master --skip-slave-move db1103 db1120
echo "===== db1103 (OLD)"; sudo db-mysql db1103 -e 'show slave status\G'
echo "===== db1120 (NEW)"; sudo db-mysql db1120 -e 'show slave status\G'
db-mysql db1120 -e "set global read_only=0"
```
[x] Promote NEW primary in dbctl, and remove read-only
```
sudo dbctl --scope eqiad section x1 set-master db1120
sudo dbctl config commit -m "Promote db1120 to x1 primary and set section read-write T300472"
```
[x] Restart puppet on both hosts:
```
sudo cumin 'db1103* or db1120*' 'run-puppet-agent -e "primary switchover T300472"'
```
**Clean up tasks:**
[x] Clean up heartbeat table(s).
```
sudo db-mysql db1120 heartbeat -e "delete from heartbeat where file like 'db1103%';"
```
[x] change events for query killer:
```
events_coredb_master.sql on the new primary db1120
events_coredb_slave.sql on the new slave db1103
```
[x] Update DNS: https://gerrit.wikimedia.org/r/c/operations/dns/+/809605
[] Update candidate primary dbctl and orchestrator notes
```
sudo dbctl instance db1103 set-candidate-master --section x1 true
sudo dbctl instance db1120 set-candidate-master --section x1 false
(dborch1001): sudo orchestrator-client -c untag -i db1120 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1103 --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 = 'x1';"
```
[] (If needed): Depool db1103 for maintenance.
```
sudo dbctl instance db1103 depool
sudo dbctl config commit -m "Depool db1103 T300472"
```
[] Apply outstanding schema changes to db1103 (if any)
[] Update/resolve this ticket.