Users Guide

Viewing Power Budget Status
Redundancy Status and Overall Power Health
Configuring Power Budget and Redundancy
Executing Power Control Operations
You can execute the following power control operation for the chassis, servers, and IOMs.
Redundancy Policies
Redundancy policy is a configurable set of properties that determine how CMC manages power to the chassis. The
following redundancy policies are configurable with or without dynamic PSU engagement:
• AC Redundancy
• Power Supply Redundancy
• No Redundancy
AC Redundancy Policy
The purpose of the AC redundancy policy is to enable a modular enclosure system to operate in a mode in which it can
tolerate AC power failures. These failures may originate in the AC power grid, the cabling and delivery, or a PSU itself.
When you configure a system for AC redundancy, the PSUs are divided into grids: PSUs in slots 1, 2, and 3 are in the first
grid while PSUs in slots 4, 5, and 6 are in the second grid. CMC manages power so that if there is a failure of either grid
the system continues to operate without any degradation. AC redundancy also tolerates failures of individual PSUs.
NOTE: Since one role of AC redundancy is to provide seamless server operation despite failure of a whole power
grid, the most power is available to maintain AC redundancy when the capacities of the two grids are
approximately equal.
NOTE: AC redundancy is only met when the load requirements do not exceed the capacity of the weakest power
grid.
AC Redundancy Levels
One PSU in each grid is the minimum configuration necessary for use as AC redundant. Additional configurations are
possible with every combination that has at least one PSU in each grid. However, to make the maximum power available
for use, the total power of the PSUs in each leg should be as close to equal as practical. The upper limit of power while
maintaining AC redundancy is the power available on the weakest of the two grids. The following figure illustrates 2
PSUs per grid and a power failure on grid 1.
If for some reason CMC is unable to maintain AC redundancy, an e-mail and/or SNMP alerts are sent to administrators if
the Redundancy Lost event is configured for alerting.
Figure 5. PSUs per grid and a power failure on grid 1
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