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Switchover s4 master (db2140 -> db2110)
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Description

When: During a pre-defined DBA maintenance windows

Affected wikis:: https://noc.wikimedia.org/conf/highlight.php?file=dblists/s4.dblist

Checklist:

NEW primary: db2110
OLD primary: db2140

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2140.codfw.wmnet h=db2110.codfw.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s4 T327739" 'A:db-section-s4'
  • Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db2110 set-weight 0
sudo dbctl config commit -m "Set db2110 with weight 0 T327739"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --replicating-master --read-only-master --only-slave-move db2140 db2110
  • Disable puppet on both nodes
sudo cumin 'db2140* or db2110*' 'disable-puppet "primary switchover T327739"'

Failover:

  • Log the failover:
!log Starting s4 codfw failover from db2140 to db2110 - T327739
  • Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db2140 db2110
echo "===== db2140 (OLD)"; sudo db-mysql db2140 -e 'show slave status\\G'
echo "===== db2110 (NEW)"; sudo db-mysql db2110 -e 'show slave status\\G'
  • Promote NEW primary in dbctl
sudo dbctl --scope codfw section s4 set-master db2110
sudo dbctl config commit -m "Promote db2110 to s4 primary T327739"
  • Restart puppet on both hosts:
sudo cumin 'db2140* or db2110*' 'run-puppet-agent -e "primary switchover T327739"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db2110 heartbeat -e "delete from heartbeat where file like 'db2140%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db2110
events_coredb_slave.sql on the new slave db2140
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2140 set-candidate-master --section s4 true
sudo dbctl instance db2110 set-candidate-master --section s4 false
(dborch1001): sudo orchestrator-client -c untag -i db2110 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db2140 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's4';"
  • (If needed): Depool db2140 for maintenance.
sudo dbctl instance db2140 depool
sudo dbctl config commit -m "Depool db2140 T327739"
  • Change db2140 weight to mimic the previous weight db2110:
sudo dbctl instance db2140 edit
  • Update/resolve this ticket.

Event Timeline

Change 882771 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db2110 to s4 master

https://gerrit.wikimedia.org/r/882771

Marostegui triaged this task as Medium priority.
Marostegui moved this task from Triage to In progress on the DBA board.

Mentioned in SAL (#wikimedia-operations) [2023-01-24T07:58:25Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Set db2110 with weight 0 T327739', diff saved to https://phabricator.wikimedia.org/P43279 and previous config saved to /var/cache/conftool/dbconfig/20230124-075824-root.json

Mentioned in SAL (#wikimedia-operations) [2023-01-24T07:58:36Z] <root@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 34 hosts with reason: Primary switchover s4 T327739

Mentioned in SAL (#wikimedia-operations) [2023-01-24T07:59:11Z] <root@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 34 hosts with reason: Primary switchover s4 T327739

Change 882771 merged by Marostegui:

[operations/puppet@production] mariadb: Promote db2110 to s4 master

https://gerrit.wikimedia.org/r/882771

Mentioned in SAL (#wikimedia-operations) [2023-01-24T08:18:24Z] <marostegui> Starting s4 codfw failover from db2140 to db2110 - T327739

Mentioned in SAL (#wikimedia-operations) [2023-01-24T08:20:26Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Promote db2110 to s4 primary T327739', diff saved to https://phabricator.wikimedia.org/P43280 and previous config saved to /var/cache/conftool/dbconfig/20230124-082025-root.json

Mentioned in SAL (#wikimedia-operations) [2023-01-24T08:21:38Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Depool db2140 T327739', diff saved to https://phabricator.wikimedia.org/P43281 and previous config saved to /var/cache/conftool/dbconfig/20230124-082138-marostegui.json

Mentioned in SAL (#wikimedia-operations) [2023-01-24T08:24:40Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Remove db2110 from API T327739', diff saved to https://phabricator.wikimedia.org/P43282 and previous config saved to /var/cache/conftool/dbconfig/20230124-082440-marostegui.json

Marostegui added a parent task: Restricted Task.Tue, Jan 24, 8:25 AM
Marostegui updated the task description. (Show Details)

Done