HP Integrated Lights-Out 4 - Manual (Page 230)

The iLO firmware monitors and configures power thresholds to support managed-power systems
(for example, using HP power capping technology). Multiple system brownout, blackout, and
thermal overloads might result when systems are allowed to boot before iLO can manage power.
The managed-power state is lost because of AC power loss, so iLO must first boot to a restore state
and allow power-on.
Brownout recovery
A brownout condition occurs when power to a running server is lost momentarily. A brownout
interrupts the operating system, but does not interrupt the iLO firmware unless it lasts more than 4
seconds.
iLO detects and recovers from power brownouts. If iLO detects that a brownout has occurred,
server power is restored after the power-on delay unless Auto-Power On is set to Always Remain
Off. After the brownout recovery, iLO firmware records a Brown-out recovery event in the
iLO Event Log.
Graceful shutdown
The ability of the iLO processor to perform a graceful shutdown requires cooperation from the
operating system. To perform a graceful shutdown, the iLO health driver must be loaded. iLO
communicates with the health driver and uses the appropriate operating system method of shutting
down the system safely to ensure that data integrity is preserved.
If the health driver is not loaded, the iLO processor attempts to use the operating system to perform
a graceful shutdown through the power button. iLO emulates a physical power-button press (iLO
momentary press) in order to prompt the operating system to shut down gracefully. The behavior
of the operating system depends on its configuration and settings for a power-button press.
For more information about the iLO drivers, see “Installing the iLO drivers” (page 33) .
The Thermal Shutdown option in the system RBSU or UEFI System Utilities allows you to disable
the automatic shutdown feature. This configuration allows the disabling of automatic shutdown
except in the most extreme conditions when physical damage might result.
Power efficiency
iLO enables you to improve power usage by using High Efficiency Mode. HEM improves the power
efficiency of the system by placing the secondary power supplies in step-down mode. When the
secondary supplies are in step-down mode, the primary supplies provide all DC power to the
system. The power supplies are more efficient because there are more DC output watts for each
watt of AC input.
NOTE: HEM is available on nonblade servers only.
When the system draws more than 70% of the maximum power output of the primary supplies,
the secondary supplies return to normal operation (that is, they exit step-down mode). When power
use drops below 60% capacity of the primary supplies, the secondary supplies return to step-down
mode. HEM enables you to achieve power consumption equal to the maximum power output of
the primary and secondary power supplies, while maintaining improved efficiency at lower
power-usage levels.
HEM does not affect power redundancy. If the primary supplies fail, the secondary supplies
immediately begin supplying DC power to the system, preventing any downtime.
You must configure HEM through the system RBSU or UEFI System Utilities. You cannot modify
these settings through iLO. For more information, see the HP ROM-Based Setup Utility User Guide
or the HP UEFI System Utilities User Guide.
The configured HEM settings are displayed on the System Information
→Server Power page.
230 Using iLO