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Switchover s5 master (db1130 -> db1100)
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/s5.dblist

Checklist:

NEW primary: db1100
OLD primary: db1130

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1130.eqiad.wmnet h=db1100.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s5 T326133" 'A:db-section-s5'
  • Set NEW primary with weight 0 (and depool it from API or vslow/dump groups if it is present).
sudo dbctl instance db1100 set-weight 0
sudo dbctl config commit -m "Set db1100 with weight 0 T326133"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1130 db1100
  • Disable puppet on both nodes
sudo cumin 'db1130* or db1100*' 'disable-puppet "primary switchover T326133"'

Failover:

  • Log the failover:
!log Starting s5 eqiad failover from db1130 to db1100 - T326133
  • Set section read-only:
sudo dbctl --scope eqiad section s5 ro "Maintenance until 06:15 UTC - T326133"
sudo dbctl config commit -m "Set s5 eqiad as read-only for maintenance - T326133"
  • Check s5 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1130 db1100
echo "===== db1130 (OLD)"; sudo db-mysql db1130 -e 'show slave status\G'
echo "===== db1100 (NEW)"; sudo db-mysql db1100 -e 'show slave status\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s5 set-master db1100
sudo dbctl --scope eqiad section s5 rw
sudo dbctl config commit -m "Promote db1100 to s5 primary and set section read-write T326133"
  • Restart puppet on both hosts:
sudo cumin 'db1130* or db1100*' 'run-puppet-agent -e "primary switchover T326133"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1100 heartbeat -e "delete from heartbeat where file like 'db1130%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1100
events_coredb_slave.sql on the new slave db1130
sudo dbctl instance db1130 set-candidate-master --section s5 true
sudo dbctl instance db1100 set-candidate-master --section s5 false
(dborch1001): sudo orchestrator-client -c untag -i db1100 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1130 --tag name=candidate
sudo db-mysql db1115 zarcillo -e "select * from masters where section = 's5';"
  • (If needed): Depool db1130 for maintenance.
sudo dbctl instance db1130 depool
sudo dbctl config commit -m "Depool db1130 T326133"
  • Change db1130 weight to mimic the previous weight db1100:
sudo dbctl instance db1130 edit
  • Apply outstanding schema changes to db1130 (if any)
  • Update/resolve this ticket.

Event Timeline

Change 874826 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1100 to s5 master

https://gerrit.wikimedia.org/r/874826

Change 874827 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/dns@master] wmnet: Update s5-master alias

https://gerrit.wikimedia.org/r/874827

Ladsgroup triaged this task as Medium priority.
Ladsgroup moved this task from Triage to Ready on the DBA board.
Ladsgroup added a subscriber: Ladsgroup.

Scheduled for next week's Tuesday (10th Jan)

Mentioned in SAL (#wikimedia-operations) [2023-01-10T06:22:28Z] <ladsgroup@cumin1001> START - Cookbook sre.hosts.downtime for 1:00:00 on 25 hosts with reason: Primary switchover s5 T326133

Mentioned in SAL (#wikimedia-operations) [2023-01-10T06:22:56Z] <ladsgroup@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 25 hosts with reason: Primary switchover s5 T326133

Mentioned in SAL (#wikimedia-operations) [2023-01-10T06:23:09Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set db1100 with weight 0 T326133', diff saved to https://phabricator.wikimedia.org/P42938 and previous config saved to /var/cache/conftool/dbconfig/20230110-062309-ladsgroup.json

Change 874826 merged by Ladsgroup:

[operations/puppet@production] mariadb: Promote db1100 to s5 master

https://gerrit.wikimedia.org/r/874826

Mentioned in SAL (#wikimedia-operations) [2023-01-10T07:01:42Z] <Amir1> Starting s5 eqiad failover from db1130 to db1100 - T326133

Mentioned in SAL (#wikimedia-operations) [2023-01-10T07:01:52Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Set s5 eqiad as read-only for maintenance - T326133', diff saved to https://phabricator.wikimedia.org/P42939 and previous config saved to /var/cache/conftool/dbconfig/20230110-070152-ladsgroup.json

Mentioned in SAL (#wikimedia-operations) [2023-01-10T07:02:23Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Promote db1100 to s5 primary and set section read-write T326133', diff saved to https://phabricator.wikimedia.org/P42940 and previous config saved to /var/cache/conftool/dbconfig/20230110-070223-ladsgroup.json

Change 874827 merged by Ladsgroup:

[operations/dns@master] wmnet: Update s5-master alias

https://gerrit.wikimedia.org/r/874827

Mentioned in SAL (#wikimedia-operations) [2023-01-10T07:06:28Z] <ladsgroup@cumin1001> dbctl commit (dc=all): 'Depool db1130 T326133', diff saved to https://phabricator.wikimedia.org/P42941 and previous config saved to /var/cache/conftool/dbconfig/20230110-070628-ladsgroup.json

Ladsgroup removed a project: Patch-For-Review.
Ladsgroup updated the task description. (Show Details)