Users Guide

remove more than one PSU, CMC again evaluates the power requirements when the second PSU is
removed to determine the firmware response. If power requirements are still not met, CMC may turn off
the low-priority servers.
Limits
• CMC does not support automated power-down of a low-priority server to allow turning-on of a
higher priority server; however, you can perform user-initiated turn-offs.
• Changes to the PSU redundancy policy are limited by the number of PSUs in the chassis. You can
select any of the two PSU redundancy configuration settings listed in Default Redundancy
Configuration.
New Server Engagement Policy
If a new server that is turned on exceeds the power available for the chassis, CMC may decrease the
power to the low-priority servers. This could happen if the administrator has configured a power limit for
the chassis that is below what would be required for full power allocation to the servers, or if insufficient
power is available in case higher power requirements by all servers in the chassis. If enough power
cannot be freed by reducing the allocated power of the low-priority servers, the new server is not
allowed to turn on.
This occurs if the administrator had configured power limit for the chassis lower than the full power
allocation to the servers or if insufficient power is available to servers requiring high power.
The following table provides the actions taken by CMC, when a new server is powered on in the scenario
described earlier.
Table 28. CMC Response When a Server Power-On is Attempted
Worst Case Power is
Available
CMC Response Server Power On
Yes No power conservation is required Allowed
No Perform power conservation:
• Power required for new server is available
• Power required for new server is not
available
Allowed
Not Allowed
If a PSU stops functioning, it results in a non-critical health state and a PSU failure event is generated. The
removal of a PSU results in a PSU removal event.
If either event results in a loss of redundancy, on the basis of power allocations, a loss of redundancy
event is generated.
If the subsequent power capacity or the user power capacity is greater than the server allocations, servers
have degraded performance or, in an extrement case, servers may be turned off. Both conditions are in
reverse-priority order; that is, the low-priority servers are turned off first.
The following table provides the firmware response to a PSU turnoff, or removal as it applies to various
PSU redundancy configurations.
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