When: Thursday May 19 6:00 UTC
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/T301312
}}NEW primary: db1163
OLD primary: db1118
- Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1118.eqiad.wmnet h=db1163.eqiad.wmnet
Failover prep:
- Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s1 T301312" 'A:db-section-s1'
- Set NEW primary with weight 0
sudo dbctl instance db1163 set-weight 0 sudo dbctl config commit -m "Set db1163 with weight 0 T301312"
- Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1118 db1163
- Disable puppet on both nodes
sudo cumin 'db1118* or db1163*' 'disable-puppet "primary switchover T301312"'
- Merge gerrit puppet change to promote NEW primary: FIXME
Failover:
- Log the failover:
!log Starting s1 eqiad failover from db1118 to db1163 - T301312
- Set section read-only:
sudo dbctl --scope eqiad section s1 ro "Maintenance until 06:15 UTC - T301312" sudo dbctl config commit -m "Set s1 eqiad as read-only for maintenance - T301312"
- Check s1 is indeed read-only
- Switch primaries:
sudo db-switchover --skip-slave-move db1118 db1163 echo "===== db1118 (OLD)"; sudo db-mysql db1118 -e 'show slave status\G' echo "===== db1163 (NEW)"; sudo db-mysql db1163 -e 'show slave status\G'
- Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s1 set-master db1163 sudo dbctl --scope eqiad section s1 rw sudo dbctl config commit -m "Promote db1163 to s1 primary and set section read-write T301312"
- Restart puppet on both hosts:
sudo cumin 'db1118* or db1163*' 'run-puppet-agent -e "primary switchover T301312"'
Clean up tasks:
- Clean up heartbeat table(s). delete from heartbeat.heartbeat where server_id=171970572
- change events for query killer:
events_coredb_master.sql on the new primary db1163 events_coredb_slave.sql on the new slave db1118
- Update DNS: FIXME
- Update candidate primary dbctl notes
sudo dbctl instance db1118 set-candidate-master --section s1 true sudo dbctl instance db1163 set-candidate-master --section s1 false
- Check zarcillo was updated
- db-switchover should do this. If it fails, do it manually: https://phabricator.wikimedia.org/P13956
- (If needed): Depool db1118 for maintenance.
sudo dbctl instance db1118 depool sudo dbctl config commit -m "Depool db1118 T301312"
- Apply outstanding schema changes to db1118 (if any): (will be done in their own tasks)
- T300402: Add namespace column to Linter table
- T300992: Add linter_template and linter_tag columns to the Linter table
- T300381: Make page_props.pp_page unsigned on wmf wikis
- T298554: Fix mismatching field type of archive.ar_timestamp on wmf wikis
- T300774: Drop fr_img_* columns
- {T304626}
- T300775: Add tl_target_id column to templatelinks
- Update/resolve this ticket.