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Switchover s1 master (db2112 -> db2203)
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Description

after T355609

When: During a pre-defined DBA maintenance windows

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

Checklist:

NEW primary: db2203
OLD primary: db2112

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2112.codfw.wmnet h=db2203.codfw.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s1 T361786" '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 db2203 set-weight 0
sudo dbctl config commit -m "Set db2203 with weight 0 T361786"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --replicating-master --read-only-master --only-slave-move db2112 db2203
  • Disable puppet on both nodes
sudo cumin 'db2112* or db2203*' 'disable-puppet "primary switchover T361786"'
  • Merge gerrit puppet change to promote NEW primary: FIXME

Failover:

  • Log the failover:
!log Starting s1 codfw failover from db2112 to db2203 - T361786
  • Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db2112 db2203
echo "===== db2112 (OLD)"; sudo db-mysql db2112 -e 'show slave status\G'
echo "===== db2203 (NEW)"; sudo db-mysql db2203 -e 'show slave status\G'
  • Promote NEW primary in dbctl
sudo dbctl --scope codfw section s1 set-master db2203
sudo dbctl config commit -m "Promote db2203 to s1 primary T361786"
  • Restart puppet on both hosts:
sudo cumin 'db2112* or db2203*' 'run-puppet-agent -e "primary switchover T361786"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db2203 heartbeat -e "delete from heartbeat where file like 'db2112%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db2203
events_coredb_slave.sql on the new slave db2112
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2112 set-candidate-master --section s1 true
sudo dbctl instance db2203 set-candidate-master --section s1 false
(dborch1001): sudo orchestrator-client -c untag -i db2203 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db2112 --tag name=candidate
sudo db-mysql db1215 zarcillo -e "select * from masters where section = 's1';"
  • (If needed): Depool db2112 for maintenance.
sudo dbctl instance db2112 depool
sudo dbctl config commit -m "Depool db2112 T361786"
  • Change db2112 weight to mimic the previous weight db2203:
sudo dbctl instance db2112 edit
  • Apply outstanding schema changes to db2112 (if any)
  • Update/resolve this ticket.

Event Timeline

Change #1016378 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db2203 to s1 master

https://gerrit.wikimedia.org/r/1016378

ABran-WMF changed the task status from Open to In Progress.Thu, Apr 4, 8:31 AM
ABran-WMF claimed this task.
ABran-WMF triaged this task as Medium priority.

Don't do this yet, I am deploying a schema change on s1.

Don't do this yet, I am deploying a schema change on s1.

This can go

Mentioned in SAL (#wikimedia-operations) [2024-04-08T07:38:48Z] <arnaudb@cumin1002> START - Cookbook sre.hosts.downtime for 1:00:00 on 37 hosts with reason: Primary switchover s1 T361786

Mentioned in SAL (#wikimedia-operations) [2024-04-08T07:39:20Z] <arnaudb@cumin1002> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 37 hosts with reason: Primary switchover s1 T361786

Mentioned in SAL (#wikimedia-operations) [2024-04-08T07:40:06Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Set db2203 with weight 0 T361786', diff saved to https://phabricator.wikimedia.org/P59781 and previous config saved to /var/cache/conftool/dbconfig/20240408-074006-arnaudb.json

Change #1016378 merged by Arnaudb:

[operations/puppet@production] mariadb: Promote db2203 to s1 master

https://gerrit.wikimedia.org/r/1016378

Mentioned in SAL (#wikimedia-operations) [2024-04-08T08:08:40Z] <arnaudb> Starting s1 codfw failover from db2112 to db2203 - T361786

Mentioned in SAL (#wikimedia-operations) [2024-04-08T08:09:10Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Promote db2203 to s1 primary T361786', diff saved to https://phabricator.wikimedia.org/P59783 and previous config saved to /var/cache/conftool/dbconfig/20240408-080910-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-04-08T08:13:20Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Bump db2112 weight T361786', diff saved to https://phabricator.wikimedia.org/P59784 and previous config saved to /var/cache/conftool/dbconfig/20240408-081320-arnaudb.json

ABran-WMF updated the task description. (Show Details)