title: spinning down the hard drive with hdparm doesn't work
body: <p>I want to spin down my hard-drive with hdparm in UBUNTU. I issue the standby signal with the following command:</p>
  
  <pre><code>sudo hdparm -S 1 /dev/sda?;sudo hdparm -C /dev/sda?
  </code></pre>
  
  <p>This should enforce a standby after 5 seconds and the next command should show all the drives in standby mode. Instead of this, I get the following output:</p>
  
  <pre><code> /dev/sda1:
   setting standby to 1 (5 seconds)
  
  /dev/sda2:
   setting standby to 1 (5 seconds)
  
  /dev/sda5:
   setting standby to 1 (5 seconds)
  
  /dev/sda1:
   drive state is:  active/idle
  
  /dev/sda2:
   drive state is:  active/idle
  
  /dev/sda5:
   drive state is:  active/idle
  </code></pre>
  
  <p>It means the drive is still active. How can I enforce the standby mode?</p>