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Switchover s7 master (db1181 -> db1136)
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Description

When: During a pre-defined DBA maintenance windows: Thursday June 2nd.

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

  • Team calendar invite

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

Checklist:

NEW primary: db1136
OLD primary: db1181

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1181.eqiad.wmnet h=db1136.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s7 T309617" '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 db1136 set-weight 0
sudo dbctl config commit -m "Set db1136 with weight 0 T309617"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1181 db1136
  • Disable puppet on both nodes
sudo cumin 'db1181* or db1136*' 'disable-puppet "primary switchover T309617"'

Failover:

  • Log the failover:
!log Starting s7 eqiad failover from db1181 to db1136 - T309617
  • Set section read-only:
sudo dbctl --scope eqiad section s7 ro "Maintenance until 06:15 UTC - T309617"
sudo dbctl config commit -m "Set s7 eqiad as read-only for maintenance - T309617"
  • Check s7 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1181 db1136
echo "===== db1181 (OLD)"; sudo db-mysql db1181 -e 'show slave status\G'
echo "===== db1136 (NEW)"; sudo db-mysql db1136 -e 'show slave status\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s7 set-master db1136
sudo dbctl --scope eqiad section s7 rw
sudo dbctl config commit -m "Promote db1136 to s7 primary and set section read-write T309617"
  • Restart puppet on both hosts:
sudo cumin 'db1181* or db1136*' 'run-puppet-agent -e "primary switchover T309617"'

Clean up tasks:

  • Clean up heartbeat table(s).
  • change events for query killer:
events_coredb_master.sql on the new primary db1136
events_coredb_slave.sql on the new slave db1181
sudo dbctl instance db1181 set-candidate-master --section s7 true
sudo dbctl instance db1136 set-candidate-master --section s7 false
(dborch1001): sudo orchestrator-client -c untag -i db1136 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1181 --tag name=candidate
sudo dbctl instance db1181 depool
sudo dbctl config commit -m "Depool db1181 T309617"
  • Apply outstanding schema changes to db1181 (if any)
  • Update/resolve this ticket.

Event Timeline

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

Change 801684 had a related patch set uploaded (by Ladsgroup; author: Ladsgroup):

[operations/puppet@production] mariadb: Promote db1136 to s7 master

https://gerrit.wikimedia.org/r/801684

Change 801685 had a related patch set uploaded (by Ladsgroup; author: Ladsgroup):

[operations/dns@master] wmnet: Update s7-master CNAME

https://gerrit.wikimedia.org/r/801685

@Ladsgroup please add the changesets for the master promotion and the CNAME update links to the task. It is easier to find them in the future.
These are the fields:

Merge gerrit puppet change to promote NEW primary: FIXME
Update DNS: FIXME

Thanks

Done. This really needs to be more automated and streamlined :(

Mentioned in SAL (#wikimedia-operations) [2022-06-01T11:30:18Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Depooling db1136 (T309617)', diff saved to https://phabricator.wikimedia.org/P29313 and previous config saved to /var/cache/conftool/dbconfig/20220601-113017-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2022-06-01T11:39:12Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Repooling after maintenance db1136 (T309617)', diff saved to https://phabricator.wikimedia.org/P29314 and previous config saved to /var/cache/conftool/dbconfig/20220601-113911-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2022-06-01T12:24:28Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Repooling after maintenance db1136 (T309617)', diff saved to https://phabricator.wikimedia.org/P29320 and previous config saved to /var/cache/conftool/dbconfig/20220601-122426-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2022-06-02T05:05:20Z] <ladsgroup@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 25 hosts with reason: Primary switchover s7 T309617

Mentioned in SAL (#wikimedia-operations) [2022-06-02T05:05:37Z] <ladsgroup@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 25 hosts with reason: Primary switchover s7 T309617

Mentioned in SAL (#wikimedia-operations) [2022-06-02T05:05:59Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set db1136 with weight 0 T309617', diff saved to https://phabricator.wikimedia.org/P29325 and previous config saved to /var/cache/conftool/dbconfig/20220602-050559-ladsgroup.json

Change 801684 merged by Ladsgroup:

[operations/puppet@production] mariadb: Promote db1136 to s7 master

https://gerrit.wikimedia.org/r/801684

Mentioned in SAL (#wikimedia-operations) [2022-06-02T06:00:08Z] <Amir1> Starting s7 eqiad failover from db1181 to db1136 - T309617

Mentioned in SAL (#wikimedia-operations) [2022-06-02T06:00:16Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set s7 eqiad as read-only for maintenance - T309617', diff saved to https://phabricator.wikimedia.org/P29333 and previous config saved to /var/cache/conftool/dbconfig/20220602-060016-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2022-06-02T06:00:54Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Promote db1136 to s7 primary and set section read-write T309617', diff saved to https://phabricator.wikimedia.org/P29334 and previous config saved to /var/cache/conftool/dbconfig/20220602-060053-ladsgroup.json

Ladsgroup updated the task description. (Show Details)
Ladsgroup updated the task description. (Show Details)

Change 801685 merged by Ladsgroup:

[operations/dns@master] wmnet: Update s7-master CNAME

https://gerrit.wikimedia.org/r/801685

Mentioned in SAL (#wikimedia-operations) [2022-06-02T06:10:39Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Depool db1181 T309617', diff saved to https://phabricator.wikimedia.org/P29335 and previous config saved to /var/cache/conftool/dbconfig/20220602-061039-ladsgroup.json

Ladsgroup updated the task description. (Show Details)
Ladsgroup updated the task description. (Show Details)

RO starts: 06:00:16
RO stops: 06:00:54

Total RO time: 38 seconds