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Switchover s1 master (db2103 -> db2112)
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Description

When: During a pre-defined DBA maintenance windows

Affected wikis:: https://noc.wikimedia.org/conf/highlight.php?file=dblists/s1.dblist

Checklist:

NEW primary: db2112
OLD primary: db2103

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2103.codfw.wmnet h=db2112.codfw.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s1 T327997" 'A:db-section-s1'
  • Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db2112 set-weight 0
sudo dbctl config commit -m "Set db2112 with weight 0 T327997"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --replicating-master --read-only-master --only-slave-move db2103 db2112
  • Disable puppet on both nodes
sudo cumin 'db2103* or db2112*' 'disable-puppet "primary switchover T327997"'

Failover:

  • Log the failover:
!log Starting s1 codfw failover from db2103 to db2112 - T327997
  • Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db2103 db2112
echo "===== db2103 (OLD)"; sudo db-mysql db2103 -e 'show slave status\\G'
echo "===== db2112 (NEW)"; sudo db-mysql db2112 -e 'show slave status\\G'
  • Promote NEW primary in dbctl
sudo dbctl --scope codfw section s1 set-master db2112
sudo dbctl config commit -m "Promote db2112 to s1 primary T327997"
  • Restart puppet on both hosts:
sudo cumin 'db2103* or db2112*' 'run-puppet-agent -e "primary switchover T327997"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db2112 heartbeat -e "delete from heartbeat where file like 'db2103%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db2112
events_coredb_slave.sql on the new slave db2103
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2103 set-candidate-master --section s1 true
sudo dbctl instance db2112 set-candidate-master --section s1 false
(dborch1001): sudo orchestrator-client -c untag -i db2112 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db2103 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's1';"
  • (If needed): Depool db2103 for maintenance.
sudo dbctl instance db2103 depool
sudo dbctl config commit -m "Depool db2103 T327997"
  • Change db2103 weight to mimic the previous weight db2112:
sudo dbctl instance db2103 edit
  • Update/resolve this ticket.

Event Timeline

Change 883513 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db2112 to s1 master

https://gerrit.wikimedia.org/r/883513

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) [2023-01-26T07:35:50Z] <marostegui@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 38 hosts with reason: Primary switchover s1 T327997

Mentioned in SAL (#wikimedia-operations) [2023-01-26T07:36:16Z] <marostegui@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 38 hosts with reason: Primary switchover s1 T327997

Mentioned in SAL (#wikimedia-operations) [2023-01-26T07:36:19Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Set db2112 with weight 0 T327997', diff saved to https://phabricator.wikimedia.org/P43358 and previous config saved to /var/cache/conftool/dbconfig/20230126-073616-root.json

Change 883513 merged by Marostegui:

[operations/puppet@production] mariadb: Promote db2112 to s1 master

https://gerrit.wikimedia.org/r/883513

Mentioned in SAL (#wikimedia-operations) [2023-01-26T08:00:07Z] <marostegui> Starting s1 codfw failover from db2103 to db2112 - T327997

Mentioned in SAL (#wikimedia-operations) [2023-01-26T08:00:34Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Promote db2112 to s1 primary T327997', diff saved to https://phabricator.wikimedia.org/P43360 and previous config saved to /var/cache/conftool/dbconfig/20230126-080033-root.json

Mentioned in SAL (#wikimedia-operations) [2023-01-26T08:02:00Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Depool db2103 T327997', diff saved to https://phabricator.wikimedia.org/P43361 and previous config saved to /var/cache/conftool/dbconfig/20230126-080159-root.json

Marostegui updated the task description. (Show Details)

Done