The Ubuntu Enterprise Cloud includes an innovative, integrated power management feature, which can provide some significant power savings in under-utilized clouds.


  1. Your node(s) must support wake-on-lan, and have it enabled in the BIOS.
  2. Each node runs a program called powernap, which attempt to do the following, in this specific order:

    • /etc/powernap/action
    • pm-suspend
    • pm-hibernate
    • poweroff
    The node should be able to execute at least one of these.

Enabling UEC Power Management

To enable UEC's Power Management, enable the POWERSAVE scheduling algorithm in your Cloud Controller's /etc/eucalyptus/eucalyptus.conf.

sudo sed -i 's/^SCHEDPOLICY=.*$/SCHEDPOLICY="POWERSAVE"/' /etc/eucalyptus.conf
sudo restart eucalyptus CLEAN=1

Monitoring UEC Power Management

By default, Eucalyptus will wait for 300 seconds (5 minutes) of inactivity on a node before putting it to sleep.

You can monitor the state by watching the cc.log:

tail -f /var/log/eucalyptus/cc.log

You can watch the counter for each node, with messages like:

[Tue Nov 24 20:13:03 2009][010063][EUCADEBUG ] node idle since 1259114895: (288/300) seconds

Once the requisite 300 idle seconds have elapsed, you can see Eucalyptus sending the powernap signal to each node, with messages like this:

[Tue Nov 25 16:09:57 2009][017368][EUCADEBUG ] sending powerdown to node:,

UEC/PowerManagement (last edited 2010-01-14 01:54:56 by dsl-173-206-1-210)