blog/data/2012-02-05-skolelinux-powersave.txt

   1 Title: Saving power with Debian Edu / Skolelinux using shutdown-at-night
   2 Tags: english, debian edu
   3 Date: 2012-02-05 09:45
   4
   5 <p>Since the Lenny version of
   6 <a href="http://www.skolelinux.org/">Debian Edu / Skolelinux</a>, a
   7 feature to save power have been included.  It is as simple as it is
   8 practical: Shut down unused clients at night, and turn them on again
   9 in the morning.  This is done using the
  10 <a href="http://packages.qa.debian.org/s/shutdown-at-night.html">shutdown-at-night</a> Debian package.</p>
  11
  12 <p>To enable this feature on a client, the machine need to be added to
  13 the netgroup shutdown-at-night-hosts.  For Debian Edu, this is done in
  14 LDAP, and once this is in place, the machine in question will check
  15 every hour from 16:00 until 06:00 to see if the machine is unused, and
  16 shut it down if it is.  If the hardware in question is supported by
  17 the
  18 <a href="http://packages.qa.debian.org/n/nvram-wakeup.html">nvram-wakeup</a>
  19 package, the BIOS is told to turn the machine back on around 07:00 +-
  20 10 minutes.  If this isn't working, one can configure wake-on-lan to
  21 try to turn on the client.  The wake-on-lan option is only documented
  22 and not enabled by default in Debian Edu.</p>
  23
  24 <p>It is important to not turn all machines on at once, as this can
  25 blow a fuse if several computers are connected to the same fuse like
  26 the common setup for a classroom.  The nvram-wakeup method only work
  27 for machines with a functioning hardware/BIOS clock.  I've seen old
  28 machines where the BIOS battery were dead and the hardware clock were
  29 starting from 0 (or was it 1990?) every boot.  If you have one of
  30 those, you have to turn on the computer manually.</p>
  31
  32 <p>The shutdown-at-night package is completely self contained, and can
  33 also be used outside the Debian Edu environment.  For those without a
  34 central LDAP server with netgroups, one can instead touch the file
  35 <tt>/etc/shutdown-at-night/shutdown-at-night</tt> to enable it.
  36 Perhaps you too can use it to save some power?</p>