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Switchover s3 master (db1123 -> db1157)
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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/s3.dblist

Checklist:

NEW primary: db1157
OLD primary: db1123

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1123.eqiad.wmnet h=db1157.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s3 T323546" '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 db1157 set-weight 0
sudo dbctl config commit -m "Set db1157 with weight 0 T323546"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1123 db1157
  • Disable puppet on both nodes
sudo cumin 'db1123* or db1157*' 'disable-puppet "primary switchover T323546"'

Failover:

  • Log the failover:
!log Starting s3 eqiad failover from db1123 to db1157 - T323546
  • Set section read-only:
sudo dbctl --scope eqiad section s3 ro "Maintenance until 06:15 UTC - T323546"
sudo dbctl config commit -m "Set s3 eqiad as read-only for maintenance - T323546"
  • Check s3 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1123 db1157
echo "===== db1123 (OLD)"; sudo db-mysql db1123 -e 'show slave status\G'
echo "===== db1157 (NEW)"; sudo db-mysql db1157 -e 'show slave status\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s3 set-master db1157
sudo dbctl --scope eqiad section s3 rw
sudo dbctl config commit -m "Promote db1157 to s3 primary and set section read-write T323546"
  • Restart puppet on both hosts:
sudo cumin 'db1123* or db1157*' 'run-puppet-agent -e "primary switchover T323546"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1157 heartbeat -e "delete from heartbeat where file like 'db1123%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1157
events_coredb_slave.sql on the new slave db1123
sudo dbctl instance db1123 set-candidate-master --section s3 true
sudo dbctl instance db1157 set-candidate-master --section s3 false
(dborch1001): sudo orchestrator-client -c untag -i db1157 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1123 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's3';"
  • (If needed): Depool db1123 for maintenance.
sudo dbctl instance db1123 depool
sudo dbctl config commit -m "Depool db1123 T323546"
  • Change db1123 weight to mimic the previous weight db1157:
sudo dbctl instance db1123 edit
  • Apply outstanding schema changes to db1123 (if any)
  • Update/resolve this ticket.

Event Timeline

Change 858380 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1157 to s3 master

https://gerrit.wikimedia.org/r/858380

Change 858381 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/858381

Marostegui moved this task from In progress to Ready on the DBA board.
Ladsgroup added a subscriber: Ladsgroup.

Scheduled for Tuesday Nov 29th.

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

Mentioned in SAL (#wikimedia-operations) [2022-11-29T05:45:48Z] <ladsgroup@cumin1001> START - Cookbook sre.hosts.downtime for 2:00:00 on 23 hosts with reason: Primary switchover s3 T323546

Mentioned in SAL (#wikimedia-operations) [2022-11-29T05:46:15Z] <ladsgroup@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 2:00:00 on 23 hosts with reason: Primary switchover s3 T323546

Mentioned in SAL (#wikimedia-operations) [2022-11-29T05:47:17Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set db1157 with weight 0 T323546', diff saved to https://phabricator.wikimedia.org/P41577 and previous config saved to /var/cache/conftool/dbconfig/20221129-054717-ladsgroup.json

Change 858380 merged by Ladsgroup:

[operations/puppet@production] mariadb: Promote db1157 to s3 master

https://gerrit.wikimedia.org/r/858380

Mentioned in SAL (#wikimedia-operations) [2022-11-29T07:00:07Z] <Amir1> Starting s3 eqiad failover from db1123 to db1157 - T323546

Mentioned in SAL (#wikimedia-operations) [2022-11-29T07:00:33Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set s3 eqiad as read-only for maintenance - T323546', diff saved to https://phabricator.wikimedia.org/P41591 and previous config saved to /var/cache/conftool/dbconfig/20221129-070032-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2022-11-29T07:01:03Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Promote db1157 to s3 primary and set section read-write T323546', diff saved to https://phabricator.wikimedia.org/P41592 and previous config saved to /var/cache/conftool/dbconfig/20221129-070102-ladsgroup.json

Change 858381 merged by Ladsgroup:

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

https://gerrit.wikimedia.org/r/858381

Mentioned in SAL (#wikimedia-operations) [2022-11-29T07:06:38Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Depool db1123 T323546', diff saved to https://phabricator.wikimedia.org/P41594 and previous config saved to /var/cache/conftool/dbconfig/20221129-070637-ladsgroup.json

Ladsgroup triaged this task as Medium priority.
Ladsgroup removed a project: Patch-For-Review.
Ladsgroup updated the task description. (Show Details)