Users Guide

Limits
● CMC does not support automated power-down of a lower priority server to allow power up of a higher priority server;
however, you can perform user-initiated power-downs.
● Changes to the PSU redundancy policy are limited by the number of PSUs in the chassis. You can select any of the three
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 allows more power for the new server. This happens if:
● The administrator had configured a power limit for the chassis that is below the power required for full power allocation to
the servers.
● Insufficient power is available for the worst-case power requirement of all servers in the chassis.
If enough power cannot be freed by reducing the power allocated to the lower priority servers, the new server may not be
allowed to turn on.
The highest amount of sustained power required to run the chassis and all the servers, including the new one, at full power is
the worst-case power requirement. If that amount of power is available, then no servers are allocated power that is less than
the worst-case power needed and the new server is also allowed to turn on.
The following table provides the actions taken by CMC when a new server is turned on in the scenario described earlier.
Table 46. 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
Disallowed
If a PSU fails, 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, based on 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 a worse case, servers may be powered down. Both conditions are in reverse-priority order, that is, the lower
priority servers are powered down first.
The following table provides the firmware response to a PSU power down or removal as it applies to various PSU redundancy
configurations.
Table 47. Chassis Impact from PSU Failure or Removal
PSU
Configuration
Dynamic PSU
Engagement
Firmware Response
Grid
Redundancy
Disabled CMC alerts you of loss of Grid Redundancy.
Power Supply
Redundancy
Disabled CMC alerts you of loss of Power Supply Redundancy.
No Redundancy Disabled Decrease power to low priority servers, if needed.
Grid
Redundancy
Enabled CMC alerts you of loss of Grid Redundancy. PSUs in standby mode (if any) are turned on
to compensate for power budget lost from the PSU failure or removal.
Power Supply
Redundancy
Enabled CMC alerts you of loss of Power Supply Redundancy. PSUs in standby mode (if any) are
turned on to compensate for power budget lost from PSU failure or removal.
No Redundancy Enabled Decrease power to low priority servers, if needed.
Managing and Monitoring Power 207