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Switchover s1 master (db1163 -> db1118)
Closed, ResolvedPublic

Description

When: During a pre-defined DBA maintenance windows

Prerequisites: https://wikitech.wikimedia.org/wiki/MariaDB/Primary_switchover

  • Team calendar invite

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

Checklist:

NEW primary: db1118
OLD primary: db1163

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1163.eqiad.wmnet h=db1118.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s1 T314380" '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 db1118 set-weight 0
sudo dbctl config commit -m "Set db1118 with weight 0 T314380"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1163 db1118
  • Disable puppet on both nodes
sudo cumin 'db1163* or db1118*' 'disable-puppet "primary switchover T314380"'
  • Merge gerrit puppet change to promote NEW primary: FIXME

Failover:

  • Log the failover:
!log Starting s1 eqiad failover from db1163 to db1118 - T314380
  • Set section read-only:
sudo dbctl --scope eqiad section s1 ro "Maintenance until 06:15 UTC - T314380"
sudo dbctl config commit -m "Set s1 eqiad as read-only for maintenance - T314380"
  • Check s1 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1163 db1118
echo "===== db1163 (OLD)"; sudo db-mysql db1163 -e 'show slave status\\G'
echo "===== db1118 (NEW)"; sudo db-mysql db1118 -e 'show slave status\\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s1 set-master db1118
sudo dbctl --scope eqiad section s1 rw
sudo dbctl config commit -m "Promote db1118 to s1 primary and set section read-write T314380"
  • Restart puppet on both hosts:
sudo cumin 'db1163* or db1118*' 'run-puppet-agent -e "primary switchover T314380"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1118 heartbeat -e "delete from heartbeat where file like 'db1163%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1118
events_coredb_slave.sql on the new slave db1163
  • Update DNS: FIXME
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db1163 set-candidate-master --section s1 true
sudo dbctl instance db1118 set-candidate-master --section s1 false
(dborch1001): sudo orchestrator-client -c untag -i db1118 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1163 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's1';"
  • (If needed): Depool db1163 for maintenance.
sudo dbctl instance db1163 depool
sudo dbctl config commit -m "Depool db1163 T314380"
  • Change db1163 weight to mimic the previous weight db1118:
sudo dbctl instance db1163 edit
  • Apply outstanding schema changes to db1163 (if any) (done separately)
  • Update/resolve this ticket.

Event Timeline

Change 819557 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1118 to s1 master

https://gerrit.wikimedia.org/r/819557

Change 819558 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/dns@master] wmnet: Update s1-master alias

https://gerrit.wikimedia.org/r/819558

Ladsgroup added a subscriber: Ladsgroup.

Scheduled for next Tuesday (16th August)

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

Mentioned in SAL (#wikimedia-operations) [2022-08-16T05:34:58Z] <ladsgroup@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 34 hosts with reason: Primary switchover s1 T314380

Mentioned in SAL (#wikimedia-operations) [2022-08-16T05:35:21Z] <ladsgroup@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 34 hosts with reason: Primary switchover s1 T314380

Mentioned in SAL (#wikimedia-operations) [2022-08-16T05:35:36Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set db1118 with weight 0 T314380', diff saved to https://phabricator.wikimedia.org/P32393 and previous config saved to /var/cache/conftool/dbconfig/20220816-053534-ladsgroup.json

Change 819557 merged by Ladsgroup:

[operations/puppet@production] mariadb: Promote db1118 to s1 master

https://gerrit.wikimedia.org/r/819557

Mentioned in SAL (#wikimedia-operations) [2022-08-16T06:04:12Z] <Amir1> Starting s1 eqiad failover from db1163 to db1118 - T314380

Mentioned in SAL (#wikimedia-operations) [2022-08-16T06:04:55Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set s1 eqiad as read-only for maintenance - T314380', diff saved to https://phabricator.wikimedia.org/P32394 and previous config saved to /var/cache/conftool/dbconfig/20220816-060455-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2022-08-16T06:05:31Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Promote db1118 to s1 primary and set section read-write T314380', diff saved to https://phabricator.wikimedia.org/P32395 and previous config saved to /var/cache/conftool/dbconfig/20220816-060530-ladsgroup.json

Change 819558 merged by Ladsgroup:

[operations/dns@master] wmnet: Update s1-master alias

https://gerrit.wikimedia.org/r/819558

Mentioned in SAL (#wikimedia-operations) [2022-08-16T06:14:14Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Depool db1163 T314380', diff saved to https://phabricator.wikimedia.org/P32396 and previous config saved to /var/cache/conftool/dbconfig/20220816-061413-ladsgroup.json

Ladsgroup updated the task description. (Show Details)