Users Guide

NOTE: With DPSE in enabled state, if power demand increases in both the two Power Redundancy policy modes, the standby
PSUs are brought Online to reclaim power.
Default Redundancy Conguration
As shown in the table here, the default redundancy conguration for a chassis depends on the number of PSUs that it contains.
Table 37. Default Redundancy Conguration
PSU Conguration Default Redundancy Policy Default Dynamic PSU Engagement Setting
Two PSUs DC Redundancy Disabled
Four PSUs DC Redundancy Disabled
Grid Redundancy
In Grid redundancy mode with four PSUs, all four PSUs are active. The two PSUs must connect to one AC power grid, while the other two
PSUs are connect to the other AC power grid.
CAUTION: To avoid a system failure, and for Grid redundancy to work eectively, there must be a balanced set of PSUs properly
cabled to separate AC grids.
If one AC grid fails, the PSUs on the functioning AC grid take over, without interrupting the servers or infrastructure.
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 is not 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 turn o. Power supply redundancy mode requires minimum two PSUs. Additional PSUs, if present, are utilized to
improve power eciency of the system if DPSE is enabled. Subsequent failures after loss of redundancy may cause the servers in the
chassis to turn o.
Power Budgeting For Hardware Modules
CMC oers a power budgeting service that allows you to congure power budget, redundancy, and dynamic power for the chassis.
The power management service enables optimization of power consumption and reallocation of power to dierent modules on the basis of
demand.
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 module, and storage adapters, PCIe cards, physical disk, main board. The chassis may have up to four servers that
communicate to the chassis through an iDRAC. For more information, see the iDRAC User’s Guide at dell.com/support/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.
178
Managing and Monitoring Power