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Switchover s3 master (db1157 -> db1223)
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/s3.dblist

Checklist:

NEW primary: db1223
OLD primary: db1157

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1157.eqiad.wmnet h=db1223.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s3 T363672" 'A:db-section-s3'
  • Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db1223 set-weight 0
sudo dbctl config commit -m "Set db1223 with weight 0 T363672"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1157 db1223
  • Disable puppet on both nodes
sudo cumin 'db1157* or db1223*' 'disable-puppet "primary switchover T363672"'

Failover:

  • Log the failover:
!log Starting s3 eqiad failover from db1157 to db1223 - T363672
  • Set section read-only:
sudo dbctl --scope eqiad section s3 ro "Maintenance until 06:15 UTC - T363672"
sudo dbctl --scope codfw section s3 ro "Maintenance until 06:15 UTC - T363672"
sudo dbctl config commit -m "Set s3 eqiad as read-only for maintenance - T363672"
  • Check s3 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1157 db1223
echo "===== db1157 (OLD)"; sudo db-mysql db1157 -e 'show slave status\G'
echo "===== db1223 (NEW)"; sudo db-mysql db1223 -e 'show slave status\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s3 set-master db1223
sudo dbctl --scope eqiad section s3 rw
sudo dbctl --scope codfw section s3 rw
sudo dbctl config commit -m "Promote db1223 to s3 primary and set section read-write T363672"
  • Restart puppet on both hosts:
sudo cumin 'db1157* or db1223*' 'run-puppet-agent -e "primary switchover T363672"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1223 heartbeat -e "delete from heartbeat where file like 'db1157%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1223
events_coredb_slave.sql on the new slave db1157
sudo dbctl instance db1157 set-candidate-master --section s3 true
sudo dbctl instance db1223 set-candidate-master --section s3 false
(dborch1001): sudo orchestrator-client -c untag -i db1223 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1157 --tag name=candidate
sudo db-mysql db1215 zarcillo -e "select * from masters where section = 's3';"
  • (If needed): Depool db1157 for maintenance.
sudo dbctl instance db1157 depool
sudo dbctl config commit -m "Depool db1157 T363672"
  • Change db1157 weight to mimic the previous weight db1223:
sudo dbctl instance db1157 edit
  • Apply outstanding schema changes to db1157 (if any) -> Pending will be done after the reimage
  • Update/resolve this ticket.

Event Timeline

Change #1024752 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1223 to s3 master

https://gerrit.wikimedia.org/r/1024752

Change #1024753 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/dns@master] wmnet: Update s3-master alias

https://gerrit.wikimedia.org/r/1024753

Mentioned in SAL (#wikimedia-operations) [2024-04-30T04:55:26Z] <marostegui@cumin1002> START - Cookbook sre.hosts.downtime for 1:00:00 on 24 hosts with reason: Primary switchover s3 T363672

Mentioned in SAL (#wikimedia-operations) [2024-04-30T04:55:42Z] <marostegui@cumin1002> dbctl commit (dc=all): 'Set db1223 with weight 0 T363672', diff saved to https://phabricator.wikimedia.org/P61449 and previous config saved to /var/cache/conftool/dbconfig/20240430-045541-marostegui.json

Mentioned in SAL (#wikimedia-operations) [2024-04-30T04:55:58Z] <marostegui@cumin1002> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 24 hosts with reason: Primary switchover s3 T363672

Change #1024752 merged by Marostegui:

[operations/puppet@production] mariadb: Promote db1223 to s3 master

https://gerrit.wikimedia.org/r/1024752

Mentioned in SAL (#wikimedia-operations) [2024-04-30T05:12:54Z] <marostegui> Starting s3 eqiad failover from db1157 to db1223 - T363672

Mentioned in SAL (#wikimedia-operations) [2024-04-30T05:13:12Z] <marostegui@cumin1002> dbctl commit (dc=all): 'Set s3 eqiad as read-only for maintenance - T363672', diff saved to https://phabricator.wikimedia.org/P61450 and previous config saved to /var/cache/conftool/dbconfig/20240430-051312-root.json

Mentioned in SAL (#wikimedia-operations) [2024-04-30T05:13:33Z] <marostegui@cumin1002> dbctl commit (dc=all): 'Promote db1223 to s3 primary and set section read-write T363672', diff saved to https://phabricator.wikimedia.org/P61451 and previous config saved to /var/cache/conftool/dbconfig/20240430-051332-root.json

Mentioned in SAL (#wikimedia-operations) [2024-04-30T05:14:19Z] <marostegui@cumin1002> dbctl commit (dc=all): 'Depool db1157 T363672', diff saved to https://phabricator.wikimedia.org/P61452 and previous config saved to /var/cache/conftool/dbconfig/20240430-051419-root.json

Change #1024753 merged by Marostegui:

[operations/dns@master] wmnet: Update s3-master alias

https://gerrit.wikimedia.org/r/1024753

Marostegui updated the task description. (Show Details)

All done