Page MenuHomePhabricator

Switchover s7 from db2118 to db2121
Closed, ResolvedPublic

Description

As part of upgrading s7 to debian buster/mariadb 10.4, we need to switch the primary to be db2121 (which is already running buster/10.4).

When: Wed 25th August at 06:00AM UTC.

Checklist:

  • Create a task to communicate the chosen date and send an announcement to the community: T289130

NEW primary: db2121
OLD primary: db2118

  • Check configuration differences between new and old primary:
sudo pt-config-diff --defaults-file /root/.my.cnf h=db2118.codfw.wmnet h=db2121.codfw.wmnet

Failover prep:

  • Silence alerts on all hosts:
sudo cookbook sre.hosts.downtime --hours 1 -r "Primary switchover s7 T289129" 'A:db-section-s7'
  • Set NEW primary with weight 0
sudo dbctl instance db2121 set-weight 0
sudo dbctl config commit -m "Set db2121 with weight 0 T289129"
  • Topology changes, move all replicas under NEW primary
sudo db-switchover --timeout=15 --only-slave-move db2118 db2121
  • Disable puppet on both nodes
sudo cumin 'db2118* or db2121*' 'disable-puppet "primary switchover T289129"'

Failover:

  • Log the failover:
!log Starting s7 codfw failover from db2118 to db2121 - T289129
  • Set section read-only:
sudo dbctl --scope codfw section s7 ro "Maintenance until 05:15 UTC - T289129"
sudo dbctl config commit -m "Set s7 codfw as read-only for maintenance - T289129"
  • Check s7 is indeed read-only
  • Switch primaries:
sudo db-switchover --skip-slave-move db2118 db2121
echo "===== db2118 (OLD)"; sudo mysql.py -h db2118 -e 'show slave status\G'
echo "===== db2121 (NEW)"; sudo mysql.py -h db2121 -e 'show slave status\G'
  • Promote NEW primary in dbctl, and remove read-only
sudo dbctl --scope codfw section s7 set-master db2121
sudo dbctl --scope codfw section s7 rw
sudo dbctl config commit -m "Promote db2121 to s7 primary and set section read-write T289129"
  • Restart puppet on both hosts:
sudo cumin 'db2118* or db2121*' 'run-puppet-agent -e "primary switchover T289129"'

Clean up tasks:

  • change events for query killer:
events_coredb_master.sql on the new primary db2121
events_coredb_slave.sql on the new slave db2118
sudo dbctl instance db2118 set-candidate-master --section s7 true
sudo dbctl instance db2121 set-candidate-master --section s7 false
  • Check tendril was updated
  • Check zarcillo was updated
  • Depool OLD primary, as it's running 10.1, replicating from a 10.4 primary
sudo dbctl instance db2118 depool
sudo dbctl config commit -m "Depool db2118 until it's reimaged to buster T289129"
  • Downtime, and stop replication for OLD primary
  • Apply outstanding schema changes to db2118 (if any)
  • Update/resolve this ticket.

Event Timeline

Kormat updated the task description. (Show Details)
Kormat updated the task description. (Show Details)

Change 713625 had a related patch set uploaded (by Kormat; author: Kormat):

[operations/puppet@production] db2121: Promote to s7 primary

https://gerrit.wikimedia.org/r/713625

Change 713626 had a related patch set uploaded (by Kormat; author: Kormat):

[operations/dns@master] wmnet: Update s7-master to db2121

https://gerrit.wikimedia.org/r/713626

This looks good, just two comments:

  • There are no schema changes to be applied
  • You might want to add that we should disable notifications + downtime + stop replication as soon as we've depooled the old master to avoid having 10.4->10.1 replication running for long
LSobanski triaged this task as Medium priority.Aug 19 2021, 8:29 AM
LSobanski moved this task from Triage to In progress on the DBA board.

Mentioned in SAL (#wikimedia-operations) [2021-08-25T05:27:03Z] <kormat@cumin1001> START - Cookbook sre.hosts.downtime for 1:04:00 on 27 hosts with reason: Primary switchover s7 T289129

Mentioned in SAL (#wikimedia-operations) [2021-08-25T05:27:24Z] <kormat@cumin1001> END (PASS) - Cookbook sre.hosts.downtime (exit_code=0) for 1:04:00 on 27 hosts with reason: Primary switchover s7 T289129

Mentioned in SAL (#wikimedia-operations) [2021-08-25T05:27:46Z] <kormat@cumin1001> dbctl commit (dc=all): 'Set db2121 with weight 0 T289129', diff saved to Unable to send diff to phaste and previous config saved to /var/cache/conftool/dbconfig/20210825-052741-kormat.json

Mentioned in SAL (#wikimedia-operations) [2021-08-25T05:28:40Z] <kormat> Moving s7 codfw replicas under db2121 - T289129

Change 713625 merged by Kormat:

[operations/puppet@production] db2121: Promote to s7 primary

https://gerrit.wikimedia.org/r/713625

Mentioned in SAL (#wikimedia-operations) [2021-08-25T06:00:48Z] <kormat> Starting s7 codfw failover from db2118 to db2121 - T289129

Mentioned in SAL (#wikimedia-operations) [2021-08-25T06:01:13Z] <kormat@cumin1001> dbctl commit (dc=all): 'Set s7 codfw as read-only for maintenance - T289129', diff saved to https://phabricator.wikimedia.org/P17075 and previous config saved to /var/cache/conftool/dbconfig/20210825-060112-kormat.json

Mentioned in SAL (#wikimedia-operations) [2021-08-25T06:02:23Z] <kormat@cumin1001> dbctl commit (dc=all): 'Promote db2121 to s7 primary and set section read-write T289129', diff saved to https://phabricator.wikimedia.org/P17076 and previous config saved to /var/cache/conftool/dbconfig/20210825-060222-kormat.json

Change 713626 merged by Kormat:

[operations/dns@master] wmnet: Update s7-master to db2121

https://gerrit.wikimedia.org/r/713626

Mentioned in SAL (#wikimedia-operations) [2021-08-25T06:07:42Z] <kormat@cumin1001> dbctl commit (dc=all): 'Depool db2118 until it's reimaged to buster T289129', diff saved to https://phabricator.wikimedia.org/P17077 and previous config saved to /var/cache/conftool/dbconfig/20210825-060742-kormat.json

Mission success.

R/O time: 06:01:04 UTC to 06:02:19 UTC, 75s.