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Switchover s7 master (db1236 -> db1181)
Closed, ResolvedPublic

Description

When: During a pre-defined DBA maintenance windows

Affected wikis:: https://noc.wikimedia.org/conf/highlight.php?file=dblists/s7.dblist

Checklist:

NEW primary: db1181
OLD primary: db1236

  • Check configuration differences between new and old primary:
$ sudo pt-config-diff --defaults-file /root/.my.cnf h=db1236.eqiad.wmnet h=db1181.eqiad.wmnet
17 config differences
Variable                  db1236                    db1181
========================= ========================= =========================
general_log_file          db1236.log                db1181.log
gtid_binlog_pos           171966638-171966638-73... 171966638-171966638-73...
gtid_binlog_state         171966638-171966638-73... 171966638-171966638-73...
gtid_current_pos          0-180359185-3359637071... 0-180359185-3359637071...
gtid_domain_id            171966638                 171974795
gtid_slave_pos            0-180359185-3359637071... 0-180359185-3359637071...
hostname                  db1236                    db1181
innodb_buffer_pool_size   405874409472              404800667648
log_bin_basename          /srv/sqldata/db1236-bin   /srv/sqldata/db1181-bin
log_bin_index             /srv/sqldata/db1236-bi... /srv/sqldata/db1181-bi...
pid_file                  /srv/sqldata/db1236.pid   /srv/sqldata/db1181.pid
report_host               db1236.eqiad.wmnet        db1181.eqiad.wmnet
rpl_semi_sync_master_e... ON                        OFF
rpl_semi_sync_slave_en... OFF                       ON
server_id                 171966638                 171974795
slow_query_log_file       db1236-slow.log           db1181-slow.log
wsrep_node_name           db1236                    db1181

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s7 T376868" 'A:db-section-s7'
  • Set NEW primary with weight 0
sudo dbctl instance db1181 set-weight 0
sudo dbctl config commit -m "Set db1181 with weight 0 T376868"
  • Depool NEW from any specific group (API, vslow, dump) if present.
sudo dbctl instance db1181 edit
# If some changes were made:
sudo dbctl config commit -m "Remove db1181 from API/vslow/dump T376868"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --replicating-master --read-only-master --only-slave-move db1236 db1181
  • Disable puppet on both nodes
sudo cumin 'db1236* or db1181*' 'disable-puppet "primary switchover T376868"'
  • Merge gerrit puppet change to promote NEW primary: FIXME

Failover:

  • Log the failover:
!log Starting s7 eqiad failover from db1236 to db1181 - T376868
  • Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db1236 db1181
echo "===== db1236 (OLD)"; sudo db-mysql db1236 -e 'show slave status\G'
echo "===== db1181 (NEW)"; sudo db-mysql db1181 -e 'show slave status\G'
  • Promote NEW primary in dbctl
sudo dbctl --scope eqiad section s7 set-master db1181
sudo dbctl config commit -m "Promote db1181 to s7 primary T376868"
  • Restart puppet on both hosts:
sudo cumin 'db1236* or db1181*' 'run-puppet-agent -e "primary switchover T376868"'

Clean up tasks:

  • Clean up heartbeat table(s).
sudo db-mysql db1181 heartbeat -e "delete from heartbeat where file like 'db1236%';"
  • change events for query killer:
curl -sS 'https://gerrit.wikimedia.org/r/plugins/gitiles/operations/software/+/refs/heads/master/dbtools/events_coredb_master.sql?format=TEXT' | base64 -d | sudo db-mysql db1181
curl -sS 'https://gerrit.wikimedia.org/r/plugins/gitiles/operations/software/+/refs/heads/master/dbtools/events_coredb_slave.sql?format=TEXT' | base64 -d | sudo db-mysql db1236
  • Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db1236 set-candidate-master --section s7 true
sudo dbctl instance db1181 set-candidate-master --section s7 false
sudo cumin 'dborch*' 'orchestrator-client -c untag -i db1181 --tag name=candidate'
sudo cumin 'dborch*' 'orchestrator-client -c tag -i db1236 --tag name=candidate'
sudo db-mysql db1215 zarcillo -e "select * from masters where section = 's7';"
  • (If needed): Depool db1236 for maintenance.
sudo dbctl instance db1236 depool
sudo dbctl config commit -m "Depool db1236 T376868"
  • Change db1236 weight to mimic the previous weight db1181:
sudo dbctl instance db1236 edit
  • Apply outstanding schema changes to db1236 (if any)
  • Update/resolve this ticket.

Event Timeline

Change #1079094 had a related patch set uploaded (by Gerrit maintenance bot; author: Gerrit maintenance bot):

[operations/puppet@production] mariadb: Promote db1181 to s7 master

https://gerrit.wikimedia.org/r/1079094

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:07:12Z] <arnaudb@cumin1002> START - Cookbook sre.hosts.downtime for 1:00:00 on 27 hosts with reason: Primary switchover s7 T376868

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:07:38Z] <arnaudb@cumin1002> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:00:00 on 27 hosts with reason: Primary switchover s7 T376868

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:08:44Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Set db1181 with weight 0 T376868', diff saved to https://phabricator.wikimedia.org/P69551 and previous config saved to /var/cache/conftool/dbconfig/20241010-070843-arnaudb.json

Change #1079094 merged by Arnaudb:

[operations/puppet@production] mariadb: Promote db1181 to s7 master

https://gerrit.wikimedia.org/r/1079094

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:14:08Z] <arnaudb> Starting s7 eqiad failover from db1236 to db1181 - T376868

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:14:54Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Promote db1181 to s7 primary T376868', diff saved to https://phabricator.wikimedia.org/P69555 and previous config saved to /var/cache/conftool/dbconfig/20241010-071453-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:17:22Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'Depool db1236 T376868', diff saved to https://phabricator.wikimedia.org/P69556 and previous config saved to /var/cache/conftool/dbconfig/20241010-071721-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:18:21Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'db1236 (re)pooling @ 5%: T376868', diff saved to https://phabricator.wikimedia.org/P69557 and previous config saved to /var/cache/conftool/dbconfig/20241010-071820-arnaudb.json

ABran-WMF claimed this task.
ABran-WMF triaged this task as Medium priority.
ABran-WMF moved this task from Triage to Done on the DBA board.

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:33:27Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'db1236 (re)pooling @ 10%: T376868', diff saved to https://phabricator.wikimedia.org/P69560 and previous config saved to /var/cache/conftool/dbconfig/20241010-073326-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-10-10T07:48:31Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'db1236 (re)pooling @ 25%: T376868', diff saved to https://phabricator.wikimedia.org/P69563 and previous config saved to /var/cache/conftool/dbconfig/20241010-074831-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-10-10T08:03:36Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'db1236 (re)pooling @ 50%: T376868', diff saved to https://phabricator.wikimedia.org/P69568 and previous config saved to /var/cache/conftool/dbconfig/20241010-080336-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-10-10T08:18:42Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'db1236 (re)pooling @ 75%: T376868', diff saved to https://phabricator.wikimedia.org/P69571 and previous config saved to /var/cache/conftool/dbconfig/20241010-081841-arnaudb.json

Mentioned in SAL (#wikimedia-operations) [2024-10-10T08:33:47Z] <arnaudb@cumin1002> dbctl commit (dc=all): 'db1236 (re)pooling @ 100%: T376868', diff saved to https://phabricator.wikimedia.org/P69573 and previous config saved to /var/cache/conftool/dbconfig/20241010-083347-arnaudb.json