title: Does Ansible manages all hosts in parallel or just five? (-f and :serial)
body: <p>I read this two ansible docs:</p>
  <p><a href="https://docs.ansible.com/ansible/latest/cli/ansible-playbook.html#cmdoption-ansible-playbook-f" rel="nofollow noreferrer">ansible-playbook -f --&gt; Statement 1</a></p>
  <p><a href="https://docs.ansible.com/ansible/latest/user_guide/playbooks_delegation.html" rel="nofollow noreferrer">ansible-playbook :serial --&gt; Statement 2</a></p>
  <p>and I found this two statements:</p>
  <h2>Statement 1</h2>
  <pre><code>-f &lt;FORKS&gt;, --forks &lt;FORKS&gt;
  </code></pre>
  <p><em>specify number of parallel processes to use (default=5)</em></p>
  <h2>Statement 2</h2>
  <p><em><strong>Rolling Update Batch Size</strong>. By default, Ansible will try to manage all of the machines referenced in a play in parallel. For a rolling update use case, you can define how many hosts Ansible should manage at a single time by using the serial keyword:</em></p>
  <h2>Question</h2>
  <p>What's correct? Does ansible uses all hosts at once or just 5?
  Or is maybe 5 just the default value of the <code>-f</code> parameter?</p>
  <p>Thanks for clarifying that!</p>
  <p>Cheers</p>