title: Postgres replication not starting after configuration
body: <p>I am trying to install and create a PostgreSQL master-slave replication.</p>
  
  <p>I have a problem after configured <code>postgresql.conf</code> and <code>pg_hba.conf</code>; I can't restart Postgres with <code>systemctl restart postgresql-11.service</code>. It complained</p>
  
  <pre><code>AUTHENTICATING for org.freedesktop.systemd1.manage-units --Authentication is required to manage system services or units
  </code></pre>
  
  <p>I also cannot start Postgres with <code>pg_ctl</code>, it complains about</p>
  
  <pre><code>unrecognized configuration parameter checkpoint_segments in file postgresql.conf line 215
  </code></pre>
  
  <p>Is it wrong to set <code>checkpoint_segments=8</code> in <code>postgresql.conf</code>?</p>
  
  <p>How can I restart Postgres?</p>
  
  <p>My <code>postgresql.conf</code>:</p>
  
  <pre><code>wal_level = hot_standby
  max_wal_senders = 3
  checkpoint_segments = 8
  wal_keep_segments = 8
  hot_standby = on
  </code></pre>