**When:** FIXME
**Checklist:**
[] Create a task to communicate the chosen date and send an announcement to the community: FIXME
[] Create a calendar entry for the maintenance, invite sre-data-persistence@
[] Add to deployments calendar. E.g.:
```
{{Deployment calendar event card
|when=2021-08-24 23:00 SF
|length=0.5
|window=Database primary switchover for s7
|who={{ircnick|kormat|Stevie Beth Mhaol}}, {{ircnick|marostegui|Manuel 'Early Bird' Arostegui}}, {{ircnick|Amir1|Amir}}
|what=https://phabricator.wikimedia.org/T300471
}}
```
NEW primary: db1131
OLD primary: db1173
[] Check configuration differences between new and old primary:
```
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1173.eqiad.wmnet h=db1131.eqiad.wmnet
```
**Failover prep:**
[] Silence alerts on all hosts:
```
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s6 T300471" 'A:db-section-s6'
```
[] Set NEW primary with weight 0
```
sudo dbctl instance db1131 set-weight 0
sudo dbctl config commit -m "Set db1131 with weight 0 T300471"
```
[] Topology changes, move all replicas under NEW primary
```
sudo db-switchover --timeout=15 --only-slave-move db1173 db1131
```
[] Disable puppet on both nodes
```
sudo cumin 'db1173* or db1131*' 'disable-puppet "primary switchover T300471"'
```
[] Merge gerrit puppet change to promote NEW primary: FIXME
**Failover:**
[] Log the failover:
```
!log Starting s6 eqiad failover from db1173 to db1131 - T300471
```
[] Set section read-only:
```
sudo dbctl --scope eqiad section s6 ro "Maintenance until 05:15 UTC - T300471"
sudo dbctl config commit -m "Set s6 eqiad as read-only for maintenance - T300471"
```
[] Check s6 is indeed read-only
[] Switch primaries:
```
sudo db-switchover --skip-slave-move db1173 db1131
echo "===== db1173 (OLD)"; sudo db-mysql db1173 -e 'show slave status\G'
echo "===== db1131 (NEW)"; sudo db-mysql db1131 -e 'show slave status\G'
```
[] Promote NEW primary in dbctl, and remove read-only
```
sudo dbctl --scope eqiad section s6 set-master db1131
sudo dbctl --scope eqiad section s6 rw
sudo dbctl config commit -m "Promote db1131 to s6 primary and set section read-write T300471"
```
[] Restart puppet on both hosts:
```
sudo cumin 'db1173* or db1131*' 'run-puppet-agent -e "primary switchover T300471"'
```
**Clean up tasks:**
[] Clean up heartbeat table(s).
[] change events for query killer:
```
events_coredb_master.sql on the new primary db1131
events_coredb_slave.sql on the new slave db1173
```
[] Update DNS: FIXME
[] Update candidate primary dbctl notes
```
sudo dbctl instance db1173 set-candidate-master --section s6 true
sudo dbctl instance db1131 set-candidate-master --section s6 false
```
[] Check zarcillo was updated
** db-switchover should do this. If it fails, do it manually: https://phabricator.wikimedia.org/P13956
[] Depool old master until its maintenance is done (if needed)
```
sudo dbctl instance db1173 depool
sudo dbctl config commit -m "Depool db1173 T300471"
```
[] Apply outstanding schema changes to db1173 (if any)
[] Update/resolve this ticket.