An increase in power demand in the Grid Redundancy configuration cause the engagement of PSUs
from the Standby state. This maintains the mirrored configuration needed for dual-grid redundancy.
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 Configuration
As shown in the table here, the default redundancy configuration for a chassis depends on the number of
PSUs that it contains.
Table 28. Default Redundancy Configuration
PSU Configuration 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 effectively, 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 off. Power supply redundancy mode
requires minimum two 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 turn off.
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 reallocation of power
to different 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.
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