title: failed to start dse solr node
body: <p>I'm trying datastax enterprise 4.8.4 on ubuntu. Installation is OK following the instructions. I can start a cassandra node with the command <code>sudo service dse start</code>. Then I want to try restart as a solr node on the same machine. So I edit the <code>/etc/default/dse</code> and set <code>SOLR_ENABLED=1</code>. Now I tried to start cassandra again, it failed.</p>
  
  <pre><code>@ubuntu:~$ sudo service dse start
  * Starting DSE daemon dse                                                                                 
  DSE daemon starting with Solr enabled (edit /etc/default/dse to disable)
  [ OK ]
  @ubuntu:~$ sudo service dse status
  * dse is running
  
  @ubuntu:~$ sudo service dse status
  * dse is not running
  </code></pre>
  
  <p>I checked the <code>/var/log/cassandra/system.log</code>. Here's the error message:</p>
  
  <pre><code>ERROR [main] 2016-01-28 16:44:02,767  CassandraDaemon.java:294 - Fatal exception during initialization   
  org.apache.cassandra.exceptions.ConfigurationException: Cannot start 
  node if snitch's data center (Solr) differs from previous data center 
  (Cassandra). Please fix the snitch configuration, decommission and 
  rebootstrap this node or use the flag -Dcassandra.ignore_dc=true.
  </code></pre>
  
  <p>The question is how could I fix it? or where do I add <code>-Dcassandra.ignore_dc=true</code>?</p>