Users Guide

In maximum power conservation mode, all servers start functioning at their minimum power levels, and
all subsequent server power allocation requests are denied. In this mode, the performance of powered
on servers may be degraded. Additional servers cannot be powered on, regardless of server priority.
The system is restored to full performance when the maximum conservation mode is cleared.
Server Power Reduction to Maintain Power Budget
CMC reduces power allocations of lower priority servers when additional power is needed to maintain
the system power consumption within the user-configured System Input Power Cap. For example,
Managing and Monitoring Power 297 when a new server is engaged, CMC may decrease power to low
priority servers to allow more power for the new server. If the amount of power is still insufficient after
reducing power allocations of the lower priority servers, CMC lowers the performance of servers until
sufficient power is freed to power the new server.
CMC reduces server power allocation in two cases:
• Overall power consumption exceeds the configurable System Input Power Cap.
• A power failure occurs in a non-redundant configuration.
110V PSUs AC Operation
Some PSUs support operation with 110V AC input. This input can exceed the allowed limit for the branch
circuit. If any PSUs are connected to 110V AC, the user needs to set CMC for normal operation of the
enclosure. If it is not set and 110V PSUs are detected, all subsequent server power allocation requests are
denied. In this case, additional servers cannot be powered on, regardless of their priority. You can set
CMC to use 110 V PSUs using the Web interface or RACADM.
Power supply entries are logged to the SEL log:
• When 110V power supplies are detected or removed.
• When the 110V AC input operation is enabled or disabled.
The overall power health is at least in Non-Critical state when the chassis is operating in 110V mode and
the user has not enabled the 110V operation. The "Warning" icon is displayed on the Web interface main
page when in Non-Critical state.
Mixed 110V and 220V operation is not supported. If CMC detects that both voltages are in use, then one
voltage is selected and those power supplies connected to the other voltage are powered off and marked
as failed.
Server Performance Over Power Redundancy
When enabled, this option favors server performance and server powerup, over maintaining power
redundancy. When disabled, the system favors power redundancy over server performance. When
disabled, then if the power 298 Managing and Monitoring Power supplies in the chassis do not provide
sufficient power, both for redundancy, as well as full performance, then to preserve redundancy, some
servers may not be:
• Granted sufficient power for full performance
• Powered on
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