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.
NOTE: If the Maximum Power Conversation Mode (MPCM) is enabled on the chassis, all power requests from a blade
server are denied. The blade server is not powered on if there is any action in the iDRAC or blade server requiring the
host to start the power cycle.
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
Remote Logging
Power consumption can be reported to a remote syslog server. Total chassis power consumption, minimum, maximum, and average
power consumption over a collection period can be logged. For more information on enabling this feature and configuring the
collection and logging interval, see the Executing Power Control Operations section.
External Power Management
CMC Power management is optionally controlled by the Dell OpenManage Power Center. For more information, see the Dell
OpenManage Power Center User’s Guide.
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