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Switchover s2 master (db1162 -> db1122)
Closed, ResolvedPublic

Description

When: Thu 11th August. During a pre-defined DBA maintenance windows

  • Team calendar invite

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

Checklist:

NEW primary: db1122
OLD primary: db1162

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1162.eqiad.wmnet h=db1122.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s2 T314368" '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 db1122 set-weight 0
sudo dbctl config commit -m "Set db1122 with weight 0 T314368"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1162 db1122
  • Disable puppet on both nodes
sudo cumin 'db1162* or db1122*' 'disable-puppet "primary switchover T314368"'
  • Merge gerrit puppet change to promote NEW primary: FIXME

Failover:

  • Log the failover:
!log Starting s2 eqiad failover from db1162 to db1122 - T314368
  • Set section read-only:
sudo dbctl --scope eqiad section s2 ro "Maintenance until 06:15 UTC - T314368"
sudo dbctl config commit -m "Set s2 eqiad as read-only for maintenance - T314368"
  • Check s2 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1162 db1122
echo "===== db1162 (OLD)"; sudo db-mysql db1162 -e 'show slave status\\G'
echo "===== db1122 (NEW)"; sudo db-mysql db1122 -e 'show slave status\\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s2 set-master db1122
sudo dbctl --scope eqiad section s2 rw
sudo dbctl config commit -m "Promote db1122 to s2 primary and set section read-write T314368"
  • Restart puppet on both hosts:
sudo cumin 'db1162* or db1122*' 'run-puppet-agent -e "primary switchover T314368"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1122 heartbeat -e "delete from heartbeat where file like 'db1162%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1122
events_coredb_slave.sql on the new slave db1162
  • Update DNS: FIXME
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db1162 set-candidate-master --section s2 true
sudo dbctl instance db1122 set-candidate-master --section s2 false
(dborch1001): sudo orchestrator-client -c untag -i db1122 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1162 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's2';"
  • (If needed): Depool db1162 for maintenance.
sudo dbctl instance db1162 depool
sudo dbctl config commit -m "Depool db1162 T314368"
  • Change db1162 weight to mimic the previous weight db1122:
sudo dbctl instance db1162 edit
  • Apply outstanding schema changes to db1162 (if any)
  • Update/resolve this ticket.

Event Timeline

Change 819525 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1122 to s2 master

https://gerrit.wikimedia.org/r/819525

Change 819546 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/dns@master] wmnet: Update s2-master alias

https://gerrit.wikimedia.org/r/819546

Mentioned in SAL (#wikimedia-operations) [2022-08-11T05:18:45Z] <ladsgroup@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 25 hosts with reason: Primary switchover s2 T314368

Mentioned in SAL (#wikimedia-operations) [2022-08-11T05:19:03Z] <ladsgroup@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 25 hosts with reason: Primary switchover s2 T314368

Mentioned in SAL (#wikimedia-operations) [2022-08-11T05:19:14Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set db1122 with weight 0 T314368', diff saved to https://phabricator.wikimedia.org/P32349 and previous config saved to /var/cache/conftool/dbconfig/20220811-051913-ladsgroup.json

Change 819525 merged by Ladsgroup:

[operations/puppet@production] mariadb: Promote db1122 to s2 master

https://gerrit.wikimedia.org/r/819525

Mentioned in SAL (#wikimedia-operations) [2022-08-11T06:00:19Z] <Amir1> Starting s2 eqiad failover from db1162 to db1122 - T314368

Mentioned in SAL (#wikimedia-operations) [2022-08-11T06:00:43Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set s2 eqiad as read-only for maintenance - T314368', diff saved to https://phabricator.wikimedia.org/P32350 and previous config saved to /var/cache/conftool/dbconfig/20220811-060042-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2022-08-11T06:01:13Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Promote db1122 to s2 primary and set section read-write T314368', diff saved to https://phabricator.wikimedia.org/P32351 and previous config saved to /var/cache/conftool/dbconfig/20220811-060113-ladsgroup.json

Change 819546 merged by Ladsgroup:

[operations/dns@master] wmnet: Update s2-master alias

https://gerrit.wikimedia.org/r/819546

Ladsgroup moved this task from In progress to Done on the DBA board.