Cisco Nexus 7718 Hardware Installation Manual page 95

Managing the Switch
Combined mode
The available power equals the combined output of all installed power supplies. There is no reserve
power. You activate this mode by using the power redundancy-mode combined command.
For example, if the power requirement for a switch is 5.2 kW and the switch has one 3-kW power
supply with 220 V input and 3.0-kW output, consider the following power planning scenarios:
The following table shows the results for each scenario.
OL-30453-01
• Scenario 1—no added power supplies
If you do not add a power supply unit, the available power (3.0 kW) is insufficient for the switch
power requirement of 5.2 kW, so the switch powers the supervisor modules, fabric modules, and
fan trays, before powering as many I/O modules as the remaining available power can support
(one or more I/O modules will not be powered).
• Scenario 2—install an extra 3-kW power supply
If you install an additional 3-kW power supply unit that can output 3.0 kW, the available power
becomes 6.0 kW. The increased amount of available power exceeds the switch power requirement
of 5.2 kW, so all of the modules and fan trays in the switch can power up.
Scenario Power
Requirement
1 5.2 kW
2 5.2 kW
Cisco Nexus 7718 Switch Site Preparation and Hardware Installation Guide
Guidelines for Configuring Power Redundancy Modes
Power Power Available
Supply 1 Supply 2 Power
Output Output
3.0 kW — 3.0 kW
3.0 kW 3.0 kW 6.0 kW
Reserve Result
Power
— Available power is less
than the power requirement
for the switch, so you
cannot power the entire
switch (some of the I/O
modules will not be able to
power up).
— Available power exceeds
the power requirement for
the switch, so the entire
switch can power up.
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