Enabling DPM on VMware 3.5 / Virtualcenter 2.5
DPM or Distributed Power Management is an experimental feature that in conjunction with DRS [Distributed Resource Scheduling], will migrate machines off of underutilized hosts in an effort to put the hosts into standby mode to conserve energy. As resource demand increases, 'Magic Packets' will be sent to the hosts to wake them from standby mode and Virtual Machines will be migrated back onto the available hosts.
Currently, I recommend only setting this to Manual since DPM is not fully support by VMware. Another issue I have with it is the inability to set the lower threshold for ON servers. Without this, DPM will shutdown all servers except one if resources permit. This obviously is not good for production since you will no longer have fault tolerance with only one server.
From a conceptual standpoint though, this is a great feature to have. I hope VMware continues to develop it in future releases.