title: elasticsearch failed to start in centos
body: <p>centos 6.7, elasticsearch 5</p>
  
  <p>I have installed the elasticsearch using rpm. But failed to start it.</p>
  
  <pre><code>error: permission denied on key 'vm.max_map_count'
  Starting elasticsearch: /usr/share/elasticsearch/bin/elasticsearch: line 198:   875 Killed                  exec "$JAVA" $ES_JAVA_OPTS -Des.path.home="$ES_HOME" -cp "$ES_CLASSPATH" org.elasticsearch.bootstrap.Elasticsearch "$@" 0&gt;&amp;-
                                                             [FAILED]
  </code></pre>