title: Switching from prefork MPM to worker MPM + php-fpm on ubuntu
body: <p>All tutorials I found were how to fresh install worker MPM + PHP-FPM, since my wordpress blog's already up and running with prefork MPM, correct me if I'm wrong in the simulated installation process: </p>
  
  <p>I'm on ubuntu and according to some tutorials, the following lines would do all the tricks:</p>
  
  <pre><code>apt-get install apache2-mpm-worker libapache2-mod-fastcgi php5-fpm php5-gd
  a2enmod actions fastcgi alias
  </code></pre>
  
  <p>Then you setup configuration in <code>/etc/apache2/conf.d/php5-fpm.conf</code>:</p>
  
  <pre><code>&lt;IfModule mod_fastcgi.c&gt;
                  AddHandler php5-fcgi .php
                  Action php5-fcgi /php5-fcgi
                  Alias /php5-fcgi /usr/lib/cgi-bin/php5-fcgi
                  FastCgiExternalServer /usr/lib/cgi-bin/php5-fcgi -host 127.0.0.1:9000 -pass-header Authorization
  &lt;/IfModule&gt;
  </code></pre>
  
  <p>After all these, restart:</p>
  
  <pre><code>service apache2 restart &amp;&amp; service php5-fpm restart
  </code></pre>
  
  <p>Question: </p>
  
  <p><strong>1)</strong> Would it cause any down time in the whole process for previously running sites with prefork MPM?</p>
  
  <p><strong>2)</strong> Do you have to change any already existent configuration files like php or mysql or apache2(would they take effect immediately after the switch without you doing anything)?</p>
  
  <p><strong>3)</strong> I've already have apc up and running, do you have to re-install/re-configure it after the switch?</p>
  
  <p><strong>4)</strong> How do you find out if apache2 is working in worker MPM mode as expected?</p>
  
  <p>Thanks a lot!</p>