Added information about the implementation of the X-SendFile module - refs #6853

documentation/optimization.html

@@ -48,6 +48,7 @@
   <li><a href="#6.Zlib-compression">Zlib compressed output</a></li>
   <li><a href="#7.High-numbers-memory">Memory considerations for high numbers of users</a></li>
   <li><a href="#8.Avoid-non-fixed-values">Avoiding non-fixed values</a></li>
+  <li><a href="#9.xsendfile">Speeding file downloads with mod_xsendfile</a></li>
 </ol>
 
 <h2><a name="1.Using-XCache"></a>1. Using xCache or APC</h2>
@@ -262,6 +263,32 @@ $platform_email['SMTP_MAILER']       = 'mail';
 </pre>
 In fact, the complete loading of mail.conf.php can also be avoided if loaded conditionally (with <i>require_once</i>) when sending an e-mail (which is the only case where it is useful).
 <hr />
+<h2><a name="#9.xsendfile"></a>Speeding file downloads with mod_xsendfile</h2>
+<p>It might have come to your attention that file downloads through Chamilo might get slow, under default conditions, in particular using Apache 2.</p>
+<p>There are several ways to fix this, one of which is removing the .htaccess inside the courses/ directory. This, however, will remove all permissions checks on the files contained in this directory, so... most of the time, not ideal unless your portal is *really* open to the world.</p>
+<p>Another technique, revealed to us by <a href="http://stackoverflow.com/users/46594/virtualblackfox">VirtualBlackFox</a> on <a href="http://stackoverflow.com/questions/3697748/fastest-way-to-serve-a-file-using-php">this Stackoverflow post</a>, is to use the X-SendFile module for Apache 2.2+ (other web servers might offer other solutions, or avoid the problem initially).</p>
+<p>Installing the X-SendFile module will depend on your operating system, but if you use Ubuntu, you'll have to check you are including the "universe" repository inside your packages sources (check /etc/apt/sources.list), then:
+<pre>
+sudo apt-get update
+sudo apt-get install libapache2-mod-xsendfile
+sudo service apache2 restart
+</pre>
+Once you're done with installing, you'll have to configure Chamilo to use it.<br />
+First, edit your VirtualHost or your Apache configuration in general (in Ubuntu, check the /etc/apache2/ or /etc/apache2/sites-available/ folder). This is done by adding the following line inside your configuration, and reloading Apache (example provided on the basis of a virtual host located in /etc/apache2/sites-available/my.chamilo.net.conf) :
+<pre>
+sudo vim /etc/apache2/sites-available/my.chamilo.net.conf
+# add the following line:
+  X-SendFile on
+# exit the file
+sudo service apache2 reload
+</pre>
+Finally, you'll have to got to your Chamilo configuration file, and add the following line at the very bottom of the file main/inc/conf/configuration.php:
+<pre>
+$_configuration['enable_x_sendfile_headers'] = true;
+</pre>
+Done! Now your downloads should go substantially faster. This is still a feature in observation. We're not sure the benefits are sufficient, so don't hesitate to let us know in <a href="https://support.chamilo.org/issues/6853">the related issue in Chamilo's tracking system</a>
+</p>
+<hr />
 <h2>Authors</h2>
 <ul>
 <li>Yannick Warnier, Zend Certified PHP Engineer, BeezNest Belgium SPRL, <a href="mailto:ywarnier@beeznest.net">ywarnier@beeznest.net</a></li>