Based on cluster resource utilization, a DRS-enabled cluster can reduce its power consumption by powering on or off ESXi hosts through the vSphere Distributed Power Management (DPM) feature.
Memory and CPU resources demanded by VMs in the cluster are compared with the total resource capacity available from the hosts in the cluster. If the cluster is providing excessive resources, one or more hosts are placed in standby mode by DPM and powered off after migrating the VM to other hosts. When the capacity provided is deemed not sufficient, DRS powers hosts on, bringing them out of standby mode and vMotion the VMs to them.
vSphere DPM can use three protocols to bring a host out of standby mode:
- Intelligent Platform Management Interface (IPMI)
- Hewlett Packard Integrated Lights-Out (iLO)
- Wake-On-LAN (WOL):
vSphere DPM can put a host in standby mode only if at least one protocol is supported. If a host supports multiple protocols, the following order is used: IPMI, iLO, WOL.