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Switchover s4 codfw master (db2110 -> db2140)
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Description

NEW primary: db2140
OLD primary: db2110

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

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s4 T318886" '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 db2140 set-weight 0
sudo dbctl config commit -m "Set db2140 with weight 0 T318886"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --read-only-master --replicating-master --timeout=25 --only-slave-move db2110 db2140
  • Disable puppet on both nodes
sudo cumin 'db2110* or db2140*' 'disable-puppet "primary switchover T318886"'

Failover:

  • Log the failover:
!log Starting s4 codfw failover from db2110 to db2140 - T318886
  • Switch primaries:
sudo db-switchover --read-only-master --replicating-master --skip-slave-move db2110 db2140
echo "===== db2110 (OLD)"; sudo db-mysql db2110 -e 'show slave status\G'
echo "===== db2140 (NEW)"; sudo db-mysql db2140 -e 'show slave status\G'
  • Promote NEW primary in dbctl
sudo dbctl --scope codfw section s4 set-master db2140
sudo dbctl config commit -m "Promote db2140 to s4 primary and set section read-write T318886"
  • Restart puppet on both hosts:
sudo cumin 'db2110* or db2140*' 'run-puppet-agent -e "primary switchover T318886"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db2140 heartbeat -e "delete from heartbeat where file like 'db2110%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db2140
events_coredb_slave.sql on the new slave db2110
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2110 set-candidate-master --section s4 true
sudo dbctl instance db2140 set-candidate-master --section s4 false
(dborch1001): sudo orchestrator-client -c untag -i db2140 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db2110 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's4';"
  • (If needed): Depool db2110 for maintenance.
sudo dbctl instance db2110 depool
sudo dbctl config commit -m "Depool db2110 T318886"
  • Change db2110 weight to mimic the previous weight db2140:
sudo dbctl instance db2110 edit
  • Update/resolve this ticket.

Event Timeline

Marostegui triaged this task as Medium priority.
Marostegui added a project: DBA.
Marostegui updated the task description. (Show Details)

Mentioned in SAL (#wikimedia-operations) [2022-09-29T05:10:54Z] <marostegui@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 34 hosts with reason: Primary switchover s4 T318886

Mentioned in SAL (#wikimedia-operations) [2022-09-29T05:11:15Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Set db2140 with weight 0 T318886', diff saved to https://phabricator.wikimedia.org/P35111 and previous config saved to /var/cache/conftool/dbconfig/20220929-051114-root.json

Mentioned in SAL (#wikimedia-operations) [2022-09-29T05:11:18Z] <marostegui@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 34 hosts with reason: Primary switchover s4 T318886

Change 836449 had a related patch set uploaded (by Marostegui; author: Marostegui):

[operations/puppet@production] mariadb: Promote db2140 to s4 codfw master

https://gerrit.wikimedia.org/r/836449

Change 836449 merged by Marostegui:

[operations/puppet@production] mariadb: Promote db2140 to s4 codfw master

https://gerrit.wikimedia.org/r/836449

Mentioned in SAL (#wikimedia-operations) [2022-09-29T05:32:18Z] <marostegui> Starting s4 codfw failover from db2110 to db2140 - T318886

Mentioned in SAL (#wikimedia-operations) [2022-09-29T05:33:02Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Promote db2140 to s4 primary and set section read-write T318886', diff saved to https://phabricator.wikimedia.org/P35115 and previous config saved to /var/cache/conftool/dbconfig/20220929-053302-root.json

Mentioned in SAL (#wikimedia-operations) [2022-09-29T05:34:08Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Depool db2110 T318886', diff saved to https://phabricator.wikimedia.org/P35116 and previous config saved to /var/cache/conftool/dbconfig/20220929-053407-root.json

Marostegui updated the task description. (Show Details)

All done

Mentioned in SAL (#wikimedia-operations) [2022-09-29T05:39:52Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Depool db2140 from API T318886', diff saved to https://phabricator.wikimedia.org/P35117 and previous config saved to /var/cache/conftool/dbconfig/20220929-053951-root.json