title: oracle database running but not listening
body: <p>I installed a 11.2020 11g EE Oracle Database</p>
  
  <pre><code>SQL&gt; select * from v$version
    2  ;
  
  BANNER
  --------------------------------------------------------------------------------
  Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
  PL/SQL Release 11.2.0.2.0 - Production
  CORE    11.2.0.2.0      Production
  TNS for Linux: Version 11.2.0.2.0 - Production
  NLSRTL Version 11.2.0.2.0 - Production
  </code></pre>
  
  <p>Initially, everything is good and it listens on port 1521 until I shut down the server.</p>
  
  <p>After restarting, I start the database by running startup</p>
  
  <pre><code>SQL&gt; startup
  ORACLE instance started.
  
  Total System Global Area 1603411968 bytes
  Fixed Size                  2226912 bytes
  Variable Size            1342178592 bytes
  Database Buffers          251658240 bytes
  Redo Buffers                7348224 bytes
  Database mounted.
  Database opened.
  </code></pre>
  
  <p>However, the database does not listen and I am unable to connect to the instance.</p>
  
  <p>I can find it in processes but not under the netstat.</p>
  
  <pre><code># ps -ef | grep pmon
  ocsgapp  12005     1  0 08:42 ?        00:00:00 ora_pmon_orcl
  root     12615 12596  0 09:05 pts/1    00:00:00 grep pmon
  
  
  # netstat -an | grep 1521
  #
  </code></pre>
  
  <p>I haven't changed anything since installation and the content of listener.ora is as the following</p>
  
  <pre><code># cat /home/ocsgapp/app/ocsgapp/product/11.2.0/dbhome_1/network/admin/listener.ora
  # listener.ora Network Configuration File: /home/ocsgapp/app/ocsgapp/product/11.2.0/dbhome_1/network/admin/listener.ora
  # Generated by Oracle configuration tools.
  
  LISTENER =
    (DESCRIPTION_LIST =
      (DESCRIPTION =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
        (ADDRESS = (PROTOCOL = TCP)(HOST = freeze.dev.unico.com.au)(PORT = 1521))
      )
    )
  
  ADR_BASE_LISTENER = /home/ocsgapp/app/ocsgapp
  </code></pre>
  
  <p>I tried to reinstall the whole database and it was listening on 1521 after installation. However, it failed to recover after another shutdown. Does anyone have idea why the db is running but fail to listen on a 1521?</p>