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Switchover s7 master (db2118 -> db2121)
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Description

When: During a pre-defined DBA maintenance windows

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

Checklist:

NEW primary: db2121
OLD primary: db2118

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2118.codfw.wmnet h=db2121.codfw.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s7 T327372" '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 db2121 set-weight 0
sudo dbctl config commit -m "Set db2121 with weight 0 T327372"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --replicating-master --read-only-master --only-slave-move db2118 db2121
  • Disable puppet on both nodes
sudo cumin 'db2118* or db2121*' 'disable-puppet "primary switchover T327372"'
  • Merge gerrit puppet change to promote NEW primary: FIXME

Failover:

  • Log the failover:
!log Starting s7 codfw failover from db2118 to db2121 - T327372
  • Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db2118 db2121
echo "===== db2118 (OLD)"; sudo db-mysql db2118 -e 'show slave status\\G'
echo "===== db2121 (NEW)"; sudo db-mysql db2121 -e 'show slave status\\G'
  • Promote NEW primary in dbctl
sudo dbctl --scope codfw section s7 set-master db2121
sudo dbctl config commit -m "Promote db2121 to s7 primary T327372"
  • Restart puppet on both hosts:
sudo cumin 'db2118* or db2121*' 'run-puppet-agent -e "primary switchover T327372"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db2121 heartbeat -e "delete from heartbeat where file like 'db2118%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db2121
events_coredb_slave.sql on the new slave db2118
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2118 set-candidate-master --section s7 true
sudo dbctl instance db2121 set-candidate-master --section s7 false
(dborch1001): sudo orchestrator-client -c untag -i db2121 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db2118 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's7';"
  • (If needed): Depool db2118 for maintenance.
sudo dbctl instance db2118 depool
sudo dbctl config commit -m "Depool db2118 T327372"
  • Change db2118 weight to mimic the previous weight db2121:
sudo dbctl instance db2118 edit
  • Apply outstanding schema changes to db2118 (if any)
  • Update/resolve this ticket.

Event Timeline

Change 881376 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db2121 to s7 master

https://gerrit.wikimedia.org/r/881376

Mentioned in SAL (#wikimedia-operations) [2023-01-19T05:41:38Z] <ladsgroup@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 30 hosts with reason: Primary switchover s7 T327372

Mentioned in SAL (#wikimedia-operations) [2023-01-19T05:42:10Z] <ladsgroup@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 30 hosts with reason: Primary switchover s7 T327372

Mentioned in SAL (#wikimedia-operations) [2023-01-19T05:42:43Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set db2121 with weight 0 T327372', diff saved to https://phabricator.wikimedia.org/P43188 and previous config saved to /var/cache/conftool/dbconfig/20230119-054243-ladsgroup.json

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

Change 881376 merged by Ladsgroup:

[operations/puppet@production] mariadb: Promote db2121 to s7 master

https://gerrit.wikimedia.org/r/881376

Mentioned in SAL (#wikimedia-operations) [2023-01-19T06:02:30Z] <Amir1> Starting s7 codfw failover from db2118 to db2121 - T327372

Mentioned in SAL (#wikimedia-operations) [2023-01-19T06:03:49Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Promote db2121 to s7 primary T327372', diff saved to https://phabricator.wikimedia.org/P43189 and previous config saved to /var/cache/conftool/dbconfig/20230119-060316-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2023-01-19T06:04:50Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Depool db2118 T327372', diff saved to https://phabricator.wikimedia.org/P43190 and previous config saved to /var/cache/conftool/dbconfig/20230119-060449-ladsgroup.json

Ladsgroup updated the task description. (Show Details)
Ladsgroup changed the edit policy from "Custom Policy" to "All Users".