Процессы операционной системы

postgres$ ps -o pid,command --ppid `head -n 1 $PGDATA/postmaster.pid`
  PID COMMAND
23588 postgres: checkpointer process   
23589 postgres: writer process   
23590 postgres: wal writer process   
23591 postgres: autovacuum launcher process   
23592 postgres: stats collector process   
23593 postgres: bgworker: logical replication launcher   

К процессам, обслуживающим буферный кэш и журнал, можно отнести:

Остановка в режиме fast

postgres$ rm /home/postgres/logfile
postgres$ pg_ctl -w -l /home/postgres/logfile -D /usr/local/pgsql/data restart
waiting for server to shut down.... done
server stopped
waiting for server to start.... done
server started

Журнал сообщений сервера:

postgres$ cat /home/postgres/logfile
2018-02-25 22:50:23.737 MSK [24125] LOG:  listening on IPv4 address "0.0.0.0", port 5432
2018-02-25 22:50:23.737 MSK [24125] LOG:  listening on IPv6 address "::", port 5432
2018-02-25 22:50:23.740 MSK [24125] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5432"
2018-02-25 22:50:23.759 MSK [24126] LOG:  database system was shut down at 2018-02-25 22:50:23 MSK
2018-02-25 22:50:23.762 MSK [24125] LOG:  database system is ready to accept connections

Остановка в режиме immediate

postgres$ rm /home/postgres/logfile
postgres$ pg_ctl -w -l /home/postgres/logfile -D /usr/local/pgsql/data restart -m immediate
waiting for server to shut down.... done
server stopped
waiting for server to start.... done
server started

Журнал сообщений сервера:

postgres$ cat /home/postgres/logfile
2018-02-25 22:50:24.030 MSK [24171] LOG:  listening on IPv4 address "0.0.0.0", port 5432
2018-02-25 22:50:24.030 MSK [24171] LOG:  listening on IPv6 address "::", port 5432
2018-02-25 22:50:24.033 MSK [24171] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5432"
2018-02-25 22:50:24.053 MSK [24172] LOG:  database system was interrupted; last known up at 2018-02-25 22:50:23 MSK
2018-02-25 22:50:24.285 MSK [24172] LOG:  database system was not properly shut down; automatic recovery in progress
2018-02-25 22:50:24.287 MSK [24172] LOG:  invalid record length at 0/17AD8BC: wanted 24, got 0
2018-02-25 22:50:24.287 MSK [24172] LOG:  redo is not required
2018-02-25 22:50:24.295 MSK [24171] LOG:  database system is ready to accept connections

Перед тем, как начать принимать соединения, СУБД выполнила восстановление (automatic recovery in progress).