User's Manual

Power Management 295
Configuration changes, such as an additional server in the chassis, may
require the System Input Power Cap to be increased. Power needs in a
modular enclosure also increase when thermal conditions change and the fans
are required to run at higher speed, which causes them to consume additional
power. Insertion of I/O modules and iKVM also increases the power needs of
the modular enclosure. A fairly small amount of power is consumed by servers
even when they are powered down to keep the management controller
powered up. Additional servers can be powered up in the modular enclosure
only if sufficient power is available. The System Input Power Cap can be
increased any time up to a maximum value of 11637 watts to allow the
power up of additional servers.
Changes in the modular enclosure that reduce the power allocation are:
• Server power off
•Server
•I/O module
• iKVM removal
• Transition of the chassis to a powered off state
You can reconfigure the System Input Power Cap when chassis is either ON
or OFF.
Server Slot Power Priority Settings
CMC allows you to set a power priority for each of the sixteen server slots in
an enclosure. The priority settings are 1 (highest) through 9 (lowest). These
settings are assigned to slots in the chassis, and the slot's priority is inherited
by any server inserted in that slot. CMC uses slot priority to preferentially
budget power to the highest priority servers in the enclosure.
According to the default server slot priority setting, power is equally
apportioned to all slots. Changing the slot priorities allows administrators to
prioritize which servers are given preference for power allocations. If the more
critical server modules are left at their default slot priority of 1, and the less
critical server modules are changed to lower priority value of 2 or higher, the
priority 1 server modules would be powered on first. These higher priority
servers would then get their maximum power allocation, while lower priority
servers may be not be allocated enough power to run at their maximum
performance or they may not even power on at all, depending on how low the
system input power cap is set and the server power requirements.