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Switchover s1 master (db1184 -> db1163)
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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/s1.dblist

Checklist:

NEW primary: db1163
OLD primary: db1184

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db1184.eqiad.wmnet h=db1163.eqiad.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s1 T366259" 'A:db-section-s1'
  • Set NEW primary with weight 0
sudo dbctl instance db1163 set-weight 0
sudo dbctl config commit -m "Set db1163 with weight 0 T366259"
  • Depool NEW from any specific group (API, vslow, dump) if present.
sudo dbctl instance db1163 edit
# If some changes were made:
sudo dbctl config commit -m "Remove db1163 from API/vslow/dump T366259"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --only-slave-move db1184 db1163
  • Disable puppet on both nodes
sudo cumin 'db1184* or db1163*' 'disable-puppet "primary switchover T366259"'
  • Merge gerrit puppet change to promote NEW primary: FIXME

Failover:

  • Log the failover:
!log Starting s1 eqiad failover from db1184 to db1163 - T366259
  • Set section read-only:
sudo dbctl --scope eqiad section s1 ro "Maintenance until 06:15 UTC - T366259"
sudo dbctl --scope codfw section s1 ro "Maintenance until 06:15 UTC - T366259"
sudo dbctl config commit -m "Set s1 eqiad as read-only for maintenance - T366259"
  • Check s1 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db1184 db1163
echo "===== db1184 (OLD)"; sudo db-mysql db1184 -e 'show slave status\G'
echo "===== db1163 (NEW)"; sudo db-mysql db1163 -e 'show slave status\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope eqiad section s1 set-master db1163
sudo dbctl --scope eqiad section s1 rw
sudo dbctl --scope codfw section s1 rw
sudo dbctl config commit -m "Promote db1163 to s1 primary and set section read-write T366259"
  • Restart puppet on both hosts:
sudo cumin 'db1184* or db1163*' 'run-puppet-agent -e "primary switchover T366259"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1163 heartbeat -e "delete from heartbeat where file like 'db1184%';"
  • change events for query killer:
events_coredb_master.sql on the new primary db1163
events_coredb_slave.sql on the new slave db1184
  • Update DNS: FIXME
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db1184 set-candidate-master --section s1 true
sudo dbctl instance db1163 set-candidate-master --section s1 false
(dborch1001): sudo orchestrator-client -c untag -i db1163 --tag name=candidate
(dborch1001): sudo orchestrator-client -c tag -i db1184 --tag name=candidate
sudo db-mysql db1215 zarcillo -e "select * from masters where section = 's1';"
  • (If needed): Depool db1184 for maintenance.
sudo dbctl instance db1184 depool
sudo dbctl config commit -m "Depool db1184 T366259"
  • Change db1184 weight to mimic the previous weight db1163:
sudo dbctl instance db1184 edit
  • Apply outstanding schema changes to db1184 (if any)
  • Update/resolve this ticket.

Event Timeline

Change #1036604 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1163 to s1 master

https://gerrit.wikimedia.org/r/1036604

Change #1036605 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/dns@master] wmnet: Update s1-master alias

https://gerrit.wikimedia.org/r/1036605

ABran-WMF changed the task status from Open to In Progress.May 31 2024, 6:56 AM
ABran-WMF claimed this task.
ABran-WMF triaged this task as Medium priority.
ABran-WMF moved this task from Triage to Ready on the DBA board.

Mentioned in SAL (#wikimedia-operations) [2024-06-04T05:27:07Z] <arnaudb@cumin1002> START - Cookbook sre.hosts.downtime for 1:00:00 on 35 hosts with reason: Primary switchover s1 T366259

Mentioned in SAL (#wikimedia-operations) [2024-06-04T05:27:36Z] <arnaudb@cumin1002> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 35 hosts with reason: Primary switchover s1 T366259

Mentioned in SAL (#wikimedia-operations) [2024-06-04T05:28:04Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Set db1163 with weight 0 T366259', diff saved to https://phabricator.wikimedia.org/P63977 and previous config saved to /var/cache/conftool/dbconfig/20240604-052803-arnaudb.json

Change #1036604 merged by Arnaudb:

[operations/puppet@production] mariadb: Promote db1163 to s1 master

https://gerrit.wikimedia.org/r/1036604

Mentioned in SAL (#wikimedia-operations) [2024-06-04T06:01:56Z] <arnaudb> Starting s1 eqiad failover from db1184 to db1163 - T366259

Mentioned in SAL (#wikimedia-operations) [2024-06-04T06:02:09Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Set s1 eqiad as read-only for maintenance - T366259', diff saved to https://phabricator.wikimedia.org/P63978 and previous config saved to /var/cache/conftool/dbconfig/20240604-060208-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-06-04T06:03:25Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Promote db1163 to s1 primary and set section read-write T366259', diff saved to https://phabricator.wikimedia.org/P63979 and previous config saved to /var/cache/conftool/dbconfig/20240604-060324-arnaudb.json

Change #1036605 merged by Arnaudb:

[operations/dns@master] wmnet: Update s1-master alias

https://gerrit.wikimedia.org/r/1036605

Mentioned in SAL (#wikimedia-operations) [2024-06-04T06:07:03Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Depool db1184 T366259', diff saved to https://phabricator.wikimedia.org/P63980 and previous config saved to /var/cache/conftool/dbconfig/20240604-060703-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-06-04T06:07:47Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'API db1163 T366259', diff saved to https://phabricator.wikimedia.org/P63981 and previous config saved to /var/cache/conftool/dbconfig/20240604-060747-arnaudb.json

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

Mentioned in SAL (#wikimedia-operations) [2024-06-04T06:09:25Z] <arnaudb@cumin1002> dbctl commit (dc=all): ' fix api db1163 vs db1184 T366259', diff saved to https://phabricator.wikimedia.org/P63982 and previous config saved to /var/cache/conftool/dbconfig/20240604-060925-arnaudb.json