User's Manual

Power Management 201
No Redundancy
Power from up to three PSUs is used to power on the entire chassis, including
the servers, IOMs, iKVM, front panel LCD, fans, and primary CMC.
NOTICE: The No Redundancy mode uses only three PSUs at a time, without
backup. Failure of one of the three PSUs being used could cause servers to lose
power and data.
Power Conservation and Power Budget Changes
The CMC can perform power conservation when the user-configured
maximum power limit is reached. Power conservation is disabled by default.
When you enable power conservation mode and the demand for power
exceeds the power limit you have set, the CMC reduces power to servers you
assign a lower priority to free power for higher priority servers and other
modules in the chassis.
If all or multiple slots in the chassis are configured with the same priority
level, the CMC decreases power to servers by increasing slot number order.
For example, if the servers in slots 1 and 2 have the same priority level, the
power for the server in slot 1 is decreased before that of the server in slot 2.
NOTE: To enable power conservation mode, see "Configuring Power Budget and
Redundancy" on page 213.
NOTE: You can assign a priority level to each of the servers in the chassis by giving
it a number from 1 through 9 inclusive. The default priority level for all servers is 5.
The lower the number, the higher the priority level. For instructions on assigning
server priority levels, see "Using RACADM" on page 215.
PSU Failure With a No Redundancy Policy
In power conservation mode, the CMC decreases power to servers when an
insufficient power event occurs, such as a PSU failure. The CMC initiates
power conservation only when the redundancy policy is set to No
Redundancy, because there may not be enough power for the chassis after a
PSU fails. After decreasing power on servers, the CMC re-evaluates the power
needs of the chassis. Power for higher priority servers is restored incrementally
while power needs remain within the power budget.
NOTE: To set the redundancy policy, see "Configuring Power Budget and
Redundancy" on page 213.