Falha ao iniciar o servidor de banco de dados PostgreSQL. - de repente [fechado]

Question

Todo o postgresql repentino foi quebrado:

$ sudo systemctl status postgresql
● postgresql.service - PostgreSQL database server
   Loaded: loaded (/usr/lib/systemd/system/postgresql.service; disabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Sat 2016-11-19 11:09:41 ICT; 8s ago
  Process: 20873 ExecStartPre=/usr/bin/postgresql-check-db-dir ${PGROOT}/data (code=exited, status=1/FAILURE)

Nov 19 11:09:40 my_notebook systemd[1]: Starting PostgreSQL database server...
Nov 19 11:09:41 my_notebook systemd[1]: postgresql.service: Control process exited, code=exited status=1
Nov 19 11:09:41 my_notebook systemd[1]: Failed to start PostgreSQL database server.
Nov 19 11:09:41 my_notebook systemd[1]: postgresql.service: Unit entered failed state.
Nov 19 11:09:41 my_notebook systemd[1]: postgresql.service: Failed with result 'exit-code'.

Qual pode ser o motivo?