User's Manual

Power Management 217
To maintain optimal efficiency, the CMC uses this information to determine
how many PSUs are required to power a given configuration and place excess
PSUs on standby. If new modules are installed, the CMC may, depending on
need and optimization, turn on new supplies.
Redundancy Policies
The redundancy policy is a configurable set of properties that determine how
the 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
You can select and configure a redundancy policy or use the default
redundancy policy for your chassis. The default redundancy configuration for
your chassis depends on how many PSUs are configured for it, as shown in
Ta b le 8 - 1 .
AC Redundancy
For AC Redundancy mode to operate at optimal power, you must have six
PSUs in your chassis. You can set your chassis to operate in AC Redundancy
mode with fewer than six PSUs, but it will operate in a degraded state.
In AC Redundancy mode, all six PSUs will be active. The three PSUs on the
left must connect to one AC power grid, while the three PSUs on the right
connect to another AC power grid.
NOTICE: To avoid a system failure and for AC Redundancy to work effectively, you
must ensure that each set of PSUs is connected to a separate AC grid.
In case one AC grid fails, the three PSUs on the functioning AC grid take over
without interruption to the servers or infrastructure.
Table 8-1. Default Redundancy Configuration
PSU Configuration Default Redundancy
Policy
Default Dynamic PSU Engagement
Setting
Six PSUs AC Redundancy Disabled
Three PSUs No Redundancy Disabled