title: Fix boot disk critical message
body: <p>I got this message from WHM.
  Do I have to fix it? Thank you.</p>
  
  <p>The filesystem “/dev/sda1”, which is mounted at “/boot”, has reached “critical” status because it is 95.63% full.</p>
  
  <p>My disk is:</p>
  
  <pre><code>Device     Size  Used   Available   Percent Used    Mount Point
  /dev/sda1   99M  90M    4.4M       96%             /boot
  /dev/sda2   451G 63G    366G       15%             /
  /usr/tmpDSK 4.0G 435M   3.4G       12%             /tmp
  </code></pre>