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Switchover s4 master (db1238 -> db1160)
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/s4.dblist

Checklist:

NEW primary: db1160
OLD primary: db1238

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1238.eqiad.wmnet h=db1160.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s4 T363689" 'A:db-section-s4'
  • Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db1160 set-weight 0
sudo dbctl config commit -m "Set db1160 with weight 0 T363689"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1238 db1160
  • Disable puppet on both nodes
sudo cumin 'db1238* or db1160*' 'disable-puppet "primary switchover T363689"'
  • Merge gerrit puppet change to promote NEW primary: FIXME

Failover:

  • Log the failover:
!log Starting s4 eqiad failover from db1238 to db1160 - T363689
  • Set section read-only:
sudo dbctl --scope eqiad section s4 ro "Maintenance until 06:15 UTC - T363689"
sudo dbctl --scope codfw section s4 ro "Maintenance until 06:15 UTC - T363689"
sudo dbctl config commit -m "Set s4 eqiad as read-only for maintenance - T363689"
  • Check s4 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1238 db1160
echo "===== db1238 (OLD)"; sudo db-mysql db1238 -e 'show slave status\G'
echo "===== db1160 (NEW)"; sudo db-mysql db1160 -e 'show slave status\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s4 set-master db1160
sudo dbctl --scope eqiad section s4 rw
sudo dbctl --scope codfw section s4 rw
sudo dbctl config commit -m "Promote db1160 to s4 primary and set section read-write T363689"
  • Restart puppet on both hosts:
sudo cumin 'db1238* or db1160*' 'run-puppet-agent -e "primary switchover T363689"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1160 heartbeat -e "delete from heartbeat where file like 'db1238%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1160
events_coredb_slave.sql on the new slave db1238
  • Update DNS: FIXME
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db1238 set-candidate-master --section s4 true
sudo dbctl instance db1160 set-candidate-master --section s4 false
(dborch1001): sudo orchestrator-client -c untag -i db1160 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1238 --tag name=candidate
sudo db-mysql db1215 zarcillo -e "select * from masters where section = 's4';"
  • (If needed): Depool db1238 for maintenance.
sudo dbctl instance db1238 depool
sudo dbctl config commit -m "Depool db1238 T363689"
  • Change db1238 weight to mimic the previous weight db1160:
sudo dbctl instance db1238 edit
  • Apply outstanding schema changes to db1238 (if any)
  • Update/resolve this ticket.

Event Timeline

Change #1024756 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1160 to s4 master

https://gerrit.wikimedia.org/r/1024756

Change #1024757 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/dns@master] wmnet: Update s4-master alias

https://gerrit.wikimedia.org/r/1024757

ABran-WMF moved this task from Triage to Ready on the DBA board.

Mentioned in SAL (#wikimedia-operations) [2024-05-23T05:47:27Z] <arnaudb@cumin1002> START - Cookbook sre.hosts.downtime for 1:00:00 on 33 hosts with reason: Primary switchover s4 T363689

Mentioned in SAL (#wikimedia-operations) [2024-05-23T05:47:55Z] <arnaudb@cumin1002> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 33 hosts with reason: Primary switchover s4 T363689

Mentioned in SAL (#wikimedia-operations) [2024-05-23T05:48:17Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Set db1160 with weight 0 T363689', diff saved to https://phabricator.wikimedia.org/P62946 and previous config saved to /var/cache/conftool/dbconfig/20240523-054816-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-05-23T06:13:05Z] <arnaudb> Starting s4 eqiad failover from db1238 to db1160 - T363689

Mentioned in SAL (#wikimedia-operations) [2024-05-23T06:14:09Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Set s4 eqiad as read-only for maintenance - T363689', diff saved to https://phabricator.wikimedia.org/P62950 and previous config saved to /var/cache/conftool/dbconfig/20240523-061408-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-05-23T06:15:25Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Promote db1160 to s4 primary and set section read-write T363689', diff saved to https://phabricator.wikimedia.org/P62951 and previous config saved to /var/cache/conftool/dbconfig/20240523-061524-arnaudb.json

Change #1034931 had a related patch set uploaded (by Arnaudb; author: Arnaudb):

[operations/puppet@production] mariadb: hotfix s4 config

https://gerrit.wikimedia.org/r/1034931

Change #1034931 merged by Arnaudb:

[operations/puppet@production] mariadb: hotfix s4 config

https://gerrit.wikimedia.org/r/1034931

Change #1034932 had a related patch set uploaded (by Arnaudb; author: Arnaudb):

[operations/dns@master] wmnet: Update s4-master alias

https://gerrit.wikimedia.org/r/1034932

Change #1034932 merged by Arnaudb:

[operations/dns@master] wmnet: Update s4-master alias

https://gerrit.wikimedia.org/r/1034932

Mentioned in SAL (#wikimedia-operations) [2024-05-23T06:30:26Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Depool db1238 T363689', diff saved to https://phabricator.wikimedia.org/P62953 and previous config saved to /var/cache/conftool/dbconfig/20240523-063025-arnaudb.json

ABran-WMF triaged this task as Medium priority.
ABran-WMF updated the task description. (Show Details)
Marostegui added subscribers: jcrespo, Marostegui.

Re-opening as there's db1150:3314 pending to be started/moved, please work with @jcrespo

ABran-WMF moved this task from Ready to Done on the DBA board.

db1150 has been moved, db1238 is being reimaged

Change #1024756 abandoned by Ladsgroup:

[operations/puppet@production] mariadb: Promote db1160 to s4 master

Reason:

https://gerrit.wikimedia.org/r/1024756

Change #1024757 abandoned by Ladsgroup:

[operations/dns@master] wmnet: Update s4-master alias

Reason:

https://gerrit.wikimedia.org/r/1024757