title: Why are shutdown scripts not guaranteed?
body: <p>In the <a href="https://cloud.google.com/compute/docs/shutdownscript" rel="noreferrer">documentation</a> it says that shutdown scripts are only run on a best effort basis and that they are not guaranteed to run. I'm wondering what conditions these would be where they wouldn't run?</p>
  
  <p><strong>Edit</strong></p>
  
  <p>As AndyJ pointed out, the documentation I linked to describes when the script is <em>supposed</em> to be run. To clarify, I have read all of that but it seemed to me that the lack of guarantee to run included the conditions in which it normally is supposed to. </p>
  
  <p>So, to better phrase my question, is the script guaranteed to run in the conditions the documentation says it runs it, or is that only when it <strong>should</strong> and not necessarily when it <strong>will</strong>?</p>