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Switchover s2 master (db2104 -> db2107)
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Description

When: During a pre-defined DBA maintenance windows

Affected wikis:: https://noc.wikimedia.org/conf/highlight.php?file=dblists/s2.dblist

Checklist:

NEW primary: db2107
OLD primary: db2104

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2104.codfw.wmnet h=db2107.codfw.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s2 T327998" 'A:db-section-s2'
  • Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db2107 set-weight 0
sudo dbctl config commit -m "Set db2107 with weight 0 T327998"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --replicating-master --read-only-master --only-slave-move db2104 db2107
  • Disable puppet on both nodes
sudo cumin 'db2104* or db2107*' 'disable-puppet "primary switchover T327998"'

Failover:

  • Log the failover:
!log Starting s2 codfw failover from db2104 to db2107 - T327998
  • Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db2104 db2107
echo "===== db2104 (OLD)"; sudo db-mysql db2104 -e 'show slave status\\G'
echo "===== db2107 (NEW)"; sudo db-mysql db2107 -e 'show slave status\\G'
  • Promote NEW primary in dbctl
sudo dbctl --scope codfw section s2 set-master db2107
sudo dbctl config commit -m "Promote db2107 to s2 primary T327998"
  • Restart puppet on both hosts:
sudo cumin 'db2104* or db2107*' 'run-puppet-agent -e "primary switchover T327998"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db2107 heartbeat -e "delete from heartbeat where file like 'db2104%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db2107
events_coredb_slave.sql on the new slave db2104
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2104 set-candidate-master --section s2 true
sudo dbctl instance db2107 set-candidate-master --section s2 false
(dborch1001): sudo orchestrator-client -c untag -i db2107 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db2104 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's2';"
  • (If needed): Depool db2104 for maintenance.
sudo dbctl instance db2104 depool
sudo dbctl config commit -m "Depool db2104 T327998"
  • Change db2104 weight to mimic the previous weight db2107:
sudo dbctl instance db2104 edit
  • Update/resolve this ticket.

Event Timeline

Change 883514 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db2107 to s2 master

https://gerrit.wikimedia.org/r/883514

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) [2023-01-26T08:04:28Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Set db2107 with weight 0 T327998', diff saved to https://phabricator.wikimedia.org/P43363 and previous config saved to /var/cache/conftool/dbconfig/20230126-080427-root.json

Mentioned in SAL (#wikimedia-operations) [2023-01-26T08:04:45Z] <marostegui@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 27 hosts with reason: Primary switchover s2 T327998

Mentioned in SAL (#wikimedia-operations) [2023-01-26T08:05:14Z] <marostegui@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 27 hosts with reason: Primary switchover s2 T327998

Change 883514 merged by Marostegui:

[operations/puppet@production] mariadb: Promote db2107 to s2 master

https://gerrit.wikimedia.org/r/883514

Mentioned in SAL (#wikimedia-operations) [2023-01-26T08:17:43Z] <marostegui> Starting s2 codfw failover from db2104 to db2107 - T327998

Mentioned in SAL (#wikimedia-operations) [2023-01-26T08:18:19Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Promote db2107 to s2 primary T327998', diff saved to https://phabricator.wikimedia.org/P43366 and previous config saved to /var/cache/conftool/dbconfig/20230126-081818-root.json

Mentioned in SAL (#wikimedia-operations) [2023-01-26T08:19:17Z] <marostegui@cumin1001> dbctl commit (dc=all): 'Depool db2104 T327998', diff saved to https://phabricator.wikimedia.org/P43367 and previous config saved to /var/cache/conftool/dbconfig/20230126-081916-root.json