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Switchover s7 master (db1181 -> db1136)
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Description

When: During a pre-defined DBA maintenance windows

Prerequisites: https://wikitech.wikimedia.org/wiki/MariaDB/Primary_switchover

  • Team calendar invite

Affected wikis:: https://noc.wikimedia.org/conf/highlight.php?file=dblists/s7.dblist

Checklist:

NEW primary: db1136
OLD primary: db1181

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1181.eqiad.wmnet h=db1136.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s7 T323117" 'A:db-section-s7'
  • Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db1136 set-weight 0
sudo dbctl config commit -m "Set db1136 with weight 0 T323117"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1181 db1136
  • Disable puppet on both nodes
sudo cumin 'db1181* or db1136*' 'disable-puppet "primary switchover T323117"'

Failover:

  • Log the failover:
!log Starting s7 eqiad failover from db1181 to db1136 - T323117
  • Set section read-only:
sudo dbctl --scope eqiad section s7 ro "Maintenance until 06:15 UTC - T323117"
sudo dbctl config commit -m "Set s7 eqiad as read-only for maintenance - T323117"
  • Check s7 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1181 db1136
echo "===== db1181 (OLD)"; sudo db-mysql db1181 -e 'show slave status\\G'
echo "===== db1136 (NEW)"; sudo db-mysql db1136 -e 'show slave status\\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s7 set-master db1136
sudo dbctl --scope eqiad section s7 rw
sudo dbctl config commit -m "Promote db1136 to s7 primary and set section read-write T323117"
  • Restart puppet on both hosts:
sudo cumin 'db1181* or db1136*' 'run-puppet-agent -e "primary switchover T323117"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1136 heartbeat -e "delete from heartbeat where file like 'db1181%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1136
events_coredb_slave.sql on the new slave db1181
sudo dbctl instance db1181 set-candidate-master --section s7 true
sudo dbctl instance db1136 set-candidate-master --section s7 false
(dborch1001): sudo orchestrator-client -c untag -i db1136 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1181 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's7';"
  • (If needed): Depool db1181 for maintenance.
sudo dbctl instance db1181 depool
sudo dbctl config commit -m "Depool db1181 T323117"
  • Change db1181 weight to mimic the previous weight db1136:
sudo dbctl instance db1181 edit
  • Apply outstanding schema changes to db1181 (if any)
  • Update/resolve this ticket.

Event Timeline

Change 856498 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1136 to s7 master

https://gerrit.wikimedia.org/r/856498

Change 856499 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/dns@master] wmnet: Update s7-master alias

https://gerrit.wikimedia.org/r/856499

Ladsgroup added a subscriber: Ladsgroup.

Scheduled for next week Thursday.

Mentioned in SAL (#wikimedia-operations) [2022-11-24T06:06:15Z] <ladsgroup@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 30 hosts with reason: Primary switchover s7 T323117

Mentioned in SAL (#wikimedia-operations) [2022-11-24T06:06:47Z] <ladsgroup@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 30 hosts with reason: Primary switchover s7 T323117

Mentioned in SAL (#wikimedia-operations) [2022-11-24T06:07:42Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set db1136 with weight 0 T323117', diff saved to https://phabricator.wikimedia.org/P40928 and previous config saved to /var/cache/conftool/dbconfig/20221124-060742-ladsgroup.json

Change 856498 merged by Ladsgroup:

[operations/puppet@production] mariadb: Promote db1136 to s7 master

https://gerrit.wikimedia.org/r/856498

Mentioned in SAL (#wikimedia-operations) [2022-11-24T07:02:04Z] <Amir1> Starting s7 eqiad failover from db1181 to db1136 - T323117

Mentioned in SAL (#wikimedia-operations) [2022-11-24T07:02:16Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set s7 eqiad as read-only for maintenance - T323117', diff saved to https://phabricator.wikimedia.org/P40931 and previous config saved to /var/cache/conftool/dbconfig/20221124-070215-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2022-11-24T07:02:51Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Promote db1136 to s7 primary and set section read-write T323117', diff saved to https://phabricator.wikimedia.org/P40932 and previous config saved to /var/cache/conftool/dbconfig/20221124-070250-ladsgroup.json

Change 856499 merged by Ladsgroup:

[operations/dns@master] wmnet: Update s7-master alias

https://gerrit.wikimedia.org/r/856499

Mentioned in SAL (#wikimedia-operations) [2022-11-24T07:05:46Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Depool db1181 T323117', diff saved to https://phabricator.wikimedia.org/P40934 and previous config saved to /var/cache/conftool/dbconfig/20221124-070546-ladsgroup.json

Ladsgroup claimed this task.
Ladsgroup removed a project: Patch-For-Review.
Ladsgroup updated the task description. (Show Details)
Ladsgroup moved this task from Ready to Done on the DBA board.