The Ubuntu Enterprise Cloud includes an innovative, integrated power management feature, which can provide some significant power savings in under-utilized clouds. == Prerequisites == 1. Your node(s) must support wake-on-lan, and have it enabled in the BIOS. 1. 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 10.1.1.243 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: 192.168.1.126, http://192.168.1.126:8775/axis2/services/EucalyptusNC }}}