2016-10-27 18:04:32 MSK [3687-1] FATAL:  database system identifier differs between the primary and standby
2016-10-27 18:04:32 MSK [3687-2] DETAIL:  The primary's identifier is 6300853119170962464, the standby's identifier is 6343126169967713718.
2016-10-27 18:04:32 MSK [3690-1] postgres@postgres PANIC:  could not open critical system index 2671
2016-10-27 18:04:32 MSK [3621-22] LOG:  received smart shutdown request
2016-10-27 18:04:32 MSK [3621-23] LOG:  server process (PID 3690) was terminated by signal 6: Aborted
2016-10-27 18:04:32 MSK [3621-24] LOG:  terminating any other active server processes
2016-10-27 18:04:33 MSK [3621-25] LOG:  abnormal database system shutdown

root@ProLiant-DL160-G6:/var/log/postgresql# psql
psql: could not connect to server: No such file or directory
    Is the server running locally and accepting
    connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

CREATE USER replica
SUPERUSER
LOGIN
CONNECTION LIMIT 1
ENCRYPTED PASSWORD 'MyStrongPassword';

Откройте этому пользователю доступ для реплицкации (pg_hba.conf):

host replication replica 127.0.0.1/0 md5

log_connections = on

max_wal_senders = 1
wal_mode = 'archive'
archive_mode = on
archive_command = 'cd .'

wal_keep_segments = 10000 # e.g. 160 GB

Сделайте бэкап (Средствами pg и rsync!)

psql -c "select pg_start_backup('Start backup for slave-server')"

rsync -cva --inplace --exclude=*pg_xlog*
${PGDATA}/ $secondnode:$PGDATA