Using the power and thermal features
Server power-on
Secure recovery
When power is applied to the server, iLO validates and starts its own firmware. If the iLO firmware fails
validation, the system automatically flashes the iLO firmware if a recovery image is available. This feature
is supported with the iLO Standard license.
During server startup, the system ROM is validated. If the active system ROM fails validation, and the
redundant system ROM is valid, the redundant system ROM becomes active. If both the active and the
redundant system ROM are invalid, and an iLO Advanced Premium Security Edition license is installed, a
firmware verification scan starts. Depending on the configured firmware verification settings, a repair is
initiated with components in the Recovery Set, or the failure is logged and you must complete the repair
manually. The server will not boot if the system ROM is not verified.
Check the IML for information about the firmware validation activities and recovery actions.
Nonblade servers
If an AC power loss occurs on a Gen10 server with iLO 5, approximately 30 seconds must elapse before
the server can power on again. If the power button is pressed during that time, it will blink, indicating a
pending request.
This delay is a result of the iLO firmware loading, authenticating, and booting. iLO processes pending
power-button requests when initialization is complete. If the server does not lose power, there is no delay.
A 30-second delay occurs only during an iLO reset. The power button is disabled until iLO is ready to
manage power.
The iLO firmware monitors and configures power thresholds to support managed-power systems (for
example, using Hewlett Packard Enterprise 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.
c-Class blade servers and Synergy compute modules
With ProLiant Gen10 blade servers and Synergy compute modules, the server cannot power on until the
system is identified, iLO determines the power requirements of the server and enclosure or frame, and
verifies that power is available. When AC power is applied to a server in an enclosure or frame, there is a
short delay. If the system does not power on when the button is pressed check the OA (c-Class) or HPE
OneView (ProLiant or Synergy) for more information. If an issue prevents server power-on, an event is
reported in the IML.
More information
iLO network Failed Flash Recovery on page 403
Brownout recovery
A brownout condition occurs when power to a running server is lost momentarily. Depending on the
duration of the brownout and the server hardware configuration, a brownout might interrupt the operating
system, but does not interrupt the iLO firmware.
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, the iLO firmware records a
Brown-out recovery
event in the iLO Event Log.
Using the power and thermal features
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