6.0

Managing Power Resources
The vSphere Distributed Power Management (DPM) feature allows a DRS cluster to reduce its power
consumption by powering hosts on and off based on cluster resource utilization.
vSphere DPM monitors the cumulative demand of all virtual machines in the cluster for memory and CPU
resources and compares this to the total available resource capacity of all hosts in the cluster. If sufficient
excess capacity is found, vSphere DPM places one or more hosts in standby mode and powers them off after
migrating their virtual machines to other hosts. Conversely, when capacity is deemed to be inadequate, DRS
brings hosts out of standby mode (powers them on) and uses vMotion to migrate virtual machines to them.
When making these calculations, vSphere DPM considers not only current demand, but it also honors any
user-specified virtual machine resource reservations.
NOTE ESXi hosts cannot automatically be brought out of standby mode unless they are running in a cluster
managed by vCenter Server.
vSphere DPM can use one of three power management protocols to bring a host out of standby mode:
Intelligent Platform Management Interface (IPMI), Hewlett-Packard Integrated Lights-Out (iLO), or Wake-
On-LAN (WOL). Each protocol requires its own hardware support and configuration. If a host does not
support any of these protocols it cannot be put into standby mode by vSphere DPM. If a host supports
multiple protocols, they are used in the following order: IPMI, iLO, WOL.
NOTE Do not disconnect a host in standby mode or move it out of the DRS cluster without first powering it
on, otherwise vCenter Server is not able to power the host back on.
Configure IPMI or iLO Settings for vSphere DPM
IPMI is a hardware-level specification and Hewlett-Packard iLO is an embedded server management
technology. Each of them describes and provides an interface for remotely monitoring and controlling
computers.
You must perform the following procedure on each host.
Prerequisites
Both IPMI and iLO require a hardware Baseboard Management Controller (BMC) to provide a gateway for
accessing hardware control functions, and allow the interface to be accessed from a remote system using
serial or LAN connections. The BMC is powered-on even when the host itself is powered-off. If properly
enabled, the BMC can respond to remote power-on commands.
If you plan to use IPMI or iLO as a wake protocol, you must configure the BMC. BMC configuration steps
vary according to model. See your vendor’s documentation for more information. With IPMI, you must also
ensure that the BMC LAN channel is configured to be always available and to allow operator-privileged
commands. On some IPMI systems, when you enable "IPMI over LAN" you must configure this in the BIOS
and specify a particular IPMI account.
vSphere DPM using only IPMI supports MD5- and plaintext-based authentication, but MD2-based
authentication is not supported. vCenter Server uses MD5 if a host's BMC reports that it is supported and
enabled for the Operator role. Otherwise, plaintext-based authentication is used if the BMC reports it is
supported and enabled. If neither MD5 nor plaintext authentication is enabled, IPMI cannot be used with
the host and vCenter Server attempts to use Wake-on-LAN.
Launch the vSphere Client and log in to a vCenter Server system.
Procedure
1 Select the host in the vSphere Client inventory.
2 Click the Configuration tab.
Chapter 25 Resource Management for Single Hosts
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