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Move Database between Servers

Checklist for moving DBs between clusters.

Pre-Move

• (prod-only) Announce downtime ~one week in advance.

• Check disk space:

  $ tco db-size ${installation}
  $ ssh ${target_server} df -h /var/lib/postgresql/
  

• (unannounced / test-only) check for users:

  $ tco sessions ${installation}
  

  If anyone is using the installation, consider postponing the move. Use tco sessions -v to see additional details.

Move

• Update db_server in config.yml and create new DBs and user:

  ansible-playbook playbook.yml -l ${INSTALLATION} -t postgres

• Start maintenance page:

  ./mntnc –auto-scale start

  This will stop the installation.

  See Maintenance Page

• (prod-only) Initialize history DB:

  copy_history_db --init-only ${source_host} ${source_db} ${target_host} ${target_db}
  

• Move main DB:

  copy_db <source_host> <source_db> <target_host> <target_db>
  

• Rename DB on old server:

  $ tco db -t postgres ${installation}
  $ ALTER DATABASE nice_<installation> RENAME TO nice_<installation>_moved;
  

  Note

  Safety mesure to ensure the old DB cannot be written to accidentally.

• Update OpenShift config:

  $ ansible-playbook playbook.yml --skip-tags ingress
  

  Note

  Skipping ingress to prevent reverting changes made by ./mntnc.

• Verify deployment succeeded:

  $ oc project nice-${installation}
  $ oc get pods
  

• Stop maintenance page:

  ./mntnc --auto-scale stop
  

• Verify installation is back online

Post-Move

• (prod-only) On the next day complete move history DB:

  copy_history_db --skip-init ${source_host} ${source_db} ${target_host} ${target_db}
  

  Note

  Do not do this overnight as we run into issues before. Do not bother copying DB for test systems unless explicitly requested.

• Remove old DBs four days later:

  tco dbs unused --ask-delete