Users Guide

CAUTION: In Grid redundancy mode, you must have balanced sets of PSUs (at least one PSU in each grid). If this
condition is not met, Grid redundancy may not be possible.
Power Supply Redundancy
When power supply redundancy is enabled, a PSU in the chassis is kept as a spare, ensuring that the failure of any one PSU does not
cause the servers or chassis to power-down. Power Supply Redundancy mode requires up to four PSUs. Additional PSUs, if present, are
utilized to improve power efficiency of the system if DPSE is enabled. Subsequent failures after loss of redundancy may cause the servers
in the chassis to power down.
No Redundancy
Power in excess of what is necessary to power the chassis is available, even on a failure, to continue to power the chassis.
CAUTION: The No Redundancy mode uses optimum PSUs when DPSE is enabled for the requirements of the chassis.
Failure of a single PSU could cause servers to lose power and data in this mode.
Power Budgeting For Hardware Modules
CMC offers a power budgeting service that allows you to configure power budget, redundancy, and dynamic power for the chassis.
The power management service enables optimization of power consumption and re-allocation of power to different modules based on
demand.
The following figure illustrates a chassis that contains a six-PSU configuration. The PSUs are numbers 1-6, starting on the left-side of the
enclosure.
Figure 17. Chassis With Six-PSU Configuration
CMC maintains a power budget for the enclosure that reserves the necessary wattage for all installed servers and components.
CMC allocates power to the CMC infrastructure and the servers in the chassis. CMC infrastructure consists of components in the
chassis, such as fans, I/O modules, and iKVM (if present). The chassis may have up to 16 servers that communicate to the chassis
through the iDRAC. For more information, see the iDRAC User’s Guide at support.dell.com/manuals.
iDRAC provides CMC with its power envelope requirements before powering up the server. The power envelope consists of the maximum
and minimum power requirements necessary to keep the server operating. iDRAC’s initial estimate is based on its initial understanding of
components in the server. After operation commences and further components are discovered, iDRAC may increase or decrease its initial
power requirements.
When a server is powered-up in an enclosure, the iDRAC software re-estimates the power requirements and requests a subsequent
change in the power envelope.
CMC grants the requested power to the server, and the allocated wattage is subtracted from the available budget. Once the server is
granted a power request, the server's iDRAC software continuously monitors the actual power consumption. Depending on the actual
Managing and Monitoring Power
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