When: During a pre-defined DBA maintenance windows
Affected wikis:: https://noc.wikimedia.org/conf/highlight.php?file=dblists/s6.dblist
Checklist:
NEW primary: db2129
OLD primary: db2214
- Check configuration differences between new and old primary:
24 config differences Variable db2214 db2129 ========================= ========================= ========================= general_log_file db2214.log db2129.log gtid_binlog_pos 171974711-171974711-19... 171970594-171970594-10... gtid_binlog_state 171974711-171974711-19... 171970594-171970594-10... gtid_current_pos 0-180359184-3070029963... 0-180359184-3049354376... gtid_domain_id 180367479 180367475 gtid_slave_pos 0-180359184-3070029963... 0-180359184-3049354376... hostname db2214 db2129 ignore_db_dirs #rocksdb innodb_buffer_pool_size 405874409472 404800667648 innodb_version 10.6.18 10.6.17 log_bin_basename /srv/sqldata/db2214-bin /srv/sqldata/db2129-bin log_bin_index /srv/sqldata/db2214-bi... /srv/sqldata/db2129-bi... optimizer_adjust_secon... 0 pid_file /srv/sqldata/db2214.pid /srv/sqldata/db2129.pid report_host db2214.codfw.wmnet db2129.codfw.wmnet rpl_semi_sync_master_e... ON OFF rpl_semi_sync_slave_en... OFF ON server_id 180367479 180367475 slave_transaction_retr... 1158,1159,1160,1161,12... 1158,1159,1160,1161,12... slow_query_log_file db2214-slow.log db2129-slow.log version 10.6.18-MariaDB-log 10.6.17-MariaDB-log version_source_revision 887bb3f73555ff8a50138a... 15c75ad083a55e198ae783... version_ssl_library OpenSSL 3.0.11 19 Sep ... OpenSSL 3.0.14 4 Jun 2024 wsrep_node_name db2214 db2129
Failover prep:
- Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s6 T374806" 'A:db-section-s6'
- Set NEW primary with weight 0 (was 400)
sudo dbctl instance db2129 set-weight 0 sudo dbctl config commit -m "Set db2129 with weight 0 T374806"
- Depool NEW from any specific group (API, vslow, dump) if present.
sudo dbctl instance db2129 edit # If some changes were made: sudo dbctl config commit -m "Remove db2129 from API/vslow/dump T374806"
- Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=25 --replicating-master --read-only-master --only-slave-move db2214 db2129
- Disable puppet on both nodes
sudo cumin 'db2214* or db2129*' 'disable-puppet "primary switchover T374806"'
- Merge gerrit puppet change to promote NEW primary: https://gerrit.wikimedia.org/r/1073038
Failover:
- Log the failover:
!log Starting s6 codfw failover from db2214 to db2129 - T374806
- Switch primaries:
sudo db-switchover --replicating-master --read-only-master --skip-slave-move db2214 db2129 echo "===== db2214 (OLD)"; sudo db-mysql db2214 -e 'show slave status\G' echo "===== db2129 (NEW)"; sudo db-mysql db2129 -e 'show slave status\G'
- Promote NEW primary in dbctl
sudo dbctl --scope codfw section s6 set-master db2129 sudo dbctl config commit -m "Promote db2129 to s6 primary T374806"
- Restart puppet on both hosts:
sudo cumin 'db2214* or db2129*' 'run-puppet-agent -e "primary switchover T374806"'
Clean up tasks:
- Clean up heartbeat table(s).
sudo db-mysql db2129 heartbeat -e "delete from heartbeat where file like 'db2214%';"
- 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 db2129 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 db2214
- Update candidate primary dbctl and orchestrator notes
sudo dbctl instance db2214 set-candidate-master --section s6 true sudo dbctl instance db2129 set-candidate-master --section s6 false sudo cumin 'dborch*' 'orchestrator-client -c untag -i db2129 --tag name=candidate' sudo cumin 'dborch*' 'orchestrator-client -c tag -i db2214 --tag name=candidate'
- Check zarcillo was updated
- db-switchover should do this. If it fails, do it manually: https://phabricator.wikimedia.org/P13956
sudo db-mysql db1215 zarcillo -e "select * from masters where section = 's6';"
- (If needed): Depool db2214 for maintenance.
sudo dbctl instance db2214 depool sudo dbctl config commit -m "Depool db2214 T374806"
- Change db2214 weight to mimic the previous weight db2129:
sudo dbctl instance db2214 edit
- Apply outstanding schema changes to db2214 (if any)
- Update/resolve this ticket.