title: How to add a disk back to sysfs after deleting it
body: <p>A fs disk failure was simulated by:</p>
  <pre class="lang-sh prettyprint-override"><code>  echo 1 &gt; /sys/block/sda/device/delete
  </code></pre>
  <p>which removes it from /dev dir. What is the procedure of adding it back?</p>