title: Difference between APC, APCu and Opcache?
body: <p>I am running a web server with the following packages;
  php-apc 3.1.7-1
  php5-fpm 5.3.10-1ubuntu3.10</p>
  
  <p>However, i have built a new server on Ubuntu 14.04 and seems like php-apc is not available anymore.</p>
  
  <p>Therefore, APC was the lifeserver for my huge traffic (100 k/daily unique visits)</p>
  
  <p>I am little bit confused about caching mechanisms on PHP.
  The new server includes these packages:
  php-apc 4.0.2-2build1
  php5-apcu 4.0.2-2build1
  php5-fpm 5.5.9+dfsg-1ubuntu4.7</p>
  
  <p>phpinfo() gives me "apc" as emulated. As far i understand, APC is replaced with APCu.</p>
  
  <p><a href="https://github.com/cepa/kickasscache" rel="noreferrer">https://github.com/cepa/kickasscache</a>
  I am running this free class for my caching, it really saves alot of cpu/mem in my case.
  But i can't understand if this is going to same with APCu?</p>
  
  <p>If its not, how can i setup a proper caching?
  Because my new server has limited resources and i need a solution.</p>
  
  <p>php -v returns</p>
  
  <pre><code>PHP 5.5.9-1ubuntu4.7 (cli) (built: Mar 16 2015 20:47:39)
  Copyright (c) 1997-2014 The PHP Group
  Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies
      with Zend OPcache v7.0.3, Copyright (c) 1999-2014, by Zend Technologies
  </code></pre>
  
  <p>Does it means OPcache enabled by default?</p>