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Switchover s2 master (db1222 -> db1162)
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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/s2.dblist

Checklist:

NEW primary: db1162
OLD primary: db1222

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1222.eqiad.wmnet h=db1162.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s2 T366687" 'A:db-section-s2'
  • Set NEW primary with weight 0
sudo dbctl instance db1162 set-weight 0
sudo dbctl config commit -m "Set db1162 with weight 0 T366687"
  • Depool NEW from any specific group (API, vslow, dump) if present.
sudo dbctl instance db1162 edit
# If some changes were made:
sudo dbctl config commit -m "Remove db1162 from API/vslow/dump T366687"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1222 db1162
  • Disable puppet on both nodes
sudo cumin 'db1222* or db1162*' 'disable-puppet "primary switchover T366687"'

Failover:

  • Log the failover:
!log Starting s2 eqiad failover from db1222 to db1162 - T366687
  • Set section read-only:
sudo dbctl --scope eqiad section s2 ro "Maintenance until 06:15 UTC - T366687"
sudo dbctl --scope codfw section s2 ro "Maintenance until 06:15 UTC - T366687"
sudo dbctl config commit -m "Set s2 eqiad as read-only for maintenance - T366687"
  • Check s2 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1222 db1162
echo "===== db1222 (OLD)"; sudo db-mysql db1222 -e 'show slave status\G'
echo "===== db1162 (NEW)"; sudo db-mysql db1162 -e 'show slave status\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s2 set-master db1162
sudo dbctl --scope eqiad section s2 rw
sudo dbctl --scope codfw section s2 rw
sudo dbctl config commit -m "Promote db1162 to s2 primary and set section read-write T366687"
  • Restart puppet on both hosts:
sudo cumin 'db1222* or db1162*' 'run-puppet-agent -e "primary switchover T366687"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1162 heartbeat -e "delete from heartbeat where file like 'db1222%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1162
events_coredb_slave.sql on the new slave db1222
sudo dbctl instance db1222 set-candidate-master --section s2 true
sudo dbctl instance db1162 set-candidate-master --section s2 false
(dborch1001): sudo orchestrator-client -c untag -i db1162 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1222 --tag name=candidate
sudo db-mysql db1215 zarcillo -e "select * from masters where section = 's2';"
  • (If needed): Depool db1222 for maintenance.
sudo dbctl instance db1222 depool
sudo dbctl config commit -m "Depool db1222 T366687"
  • Change db1222 weight to mimic the previous weight db1162:
sudo dbctl instance db1222 edit
  • Update/resolve this ticket.

Event Timeline

Change #1038795 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1162 to s2 master

https://gerrit.wikimedia.org/r/1038795

Change #1038796 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/1038796

I will get this done on Tuesday next week

Marostegui moved this task from Triage to Ready on the DBA board.

Mentioned in SAL (#wikimedia-operations) [2024-06-11T04:33:25Z] <marostegui@cumin1002> START - Cookbook sre.hosts.downtime for 1:00:00 on 26 hosts with reason: Primary switchover s2 T366687

Mentioned in SAL (#wikimedia-operations) [2024-06-11T04:33:34Z] <marostegui@cumin1002> dbctl commit (dc=all): 'Set db1162 with weight 0 T366687', diff saved to https://phabricator.wikimedia.org/P64568 and previous config saved to /var/cache/conftool/dbconfig/20240611-043333-marostegui.json

Mentioned in SAL (#wikimedia-operations) [2024-06-11T04:33:48Z] <marostegui@cumin1002> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 26 hosts with reason: Primary switchover s2 T366687

Change #1038795 merged by Marostegui:

[operations/puppet@production] mariadb: Promote db1162 to s2 master

https://gerrit.wikimedia.org/r/1038795

Mentioned in SAL (#wikimedia-operations) [2024-06-11T04:53:25Z] <marostegui> Starting s2 eqiad failover from db1222 to db1162 - T366687

Mentioned in SAL (#wikimedia-operations) [2024-06-11T04:53:41Z] <marostegui@cumin1002> dbctl commit (dc=all): 'Set s2 eqiad as read-only for maintenance - T366687', diff saved to https://phabricator.wikimedia.org/P64571 and previous config saved to /var/cache/conftool/dbconfig/20240611-045341-root.json

Mentioned in SAL (#wikimedia-operations) [2024-06-11T04:54:01Z] <marostegui@cumin1002> dbctl commit (dc=all): 'Promote db1162 to s2 primary and set section read-write T366687', diff saved to https://phabricator.wikimedia.org/P64572 and previous config saved to /var/cache/conftool/dbconfig/20240611-045359-root.json

Mentioned in SAL (#wikimedia-operations) [2024-06-11T04:54:48Z] <marostegui@cumin1002> dbctl commit (dc=all): 'Depool db1222 T366687', diff saved to https://phabricator.wikimedia.org/P64573 and previous config saved to /var/cache/conftool/dbconfig/20240611-045447-root.json

Change #1038796 merged by Marostegui:

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

https://gerrit.wikimedia.org/r/1038796

Marostegui updated the task description. (Show Details)

This is done