4.3. Power Management

The Red Hat Virtualization Manager is capable of rebooting hosts that have entered a non-operational or non-responsive state, as well as preparing to power off under-utilized hosts to save power. This functionality depends on a properly configured power management device. The Red Hat Virtualization environment supports the following power management devices:

Red Hat recommends that HP servers use ilo3 or ilo4, Dell servers use drac5 or Integrated Dell Remote Access Controllers (idrac), and IBM servers use ipmilan. Integrated Management Module (IMM) uses the IPMI protocol, and therefore IMM users can use ipmilan.

In order to communicate with the listed power management devices, the Red Hat Virtualization Manager makes use of fence agents. The Red Hat Virtualization Manager allows administrators to configure a fence agent for the power management device in their environment with parameters the device will accept and respond to. Basic configuration options can be configured using the graphical user interface. Special configuration options can also be entered, and are passed un-parsed to the fence device. Special configuration options are specific to a given fence device, while basic configuration options are for functionalities provided by all supported power management devices. The basic functionalities provided by all power management devices are:

Best practice is to test the power management configuration once when initially configuring it, and occasionally after that to ensure continued functionality.

Resilience is provided by properly configured power management devices in all of the hosts in an environment. Fencing agents allow the Red Hat Virtualization Manager to communicate with host power management devices to bypass the operating system on a problem host, and isolate the host from the rest of its environment by rebooting it. The Manager can then reassign the SPM role, if it was held by the problem host, and safely restart any highly available virtual machines on other hosts.