Cisco MDS 9000 Series Configuration Manual page 165

Managing System Hardware
• When you change the configuration from combined to redundant mode and the system detects a power
supply that has a capacity lower than the current usage, the power supply is shut down. If both power
supplies have a lower capacity than the current system usage, the configuration is not allowed.
Scenario 1: You have the following usage figures configured:
Power supply 1 = 2500 W
Additional Power supply 2 = 1800 W
Current Usage = 2000 W
Current mode = combined mode (so current capacity is 3600 W)
You decide to change the switch to redundant mode. Then power supply 2 is
shut down.
Reason: 1800 W is the lesser of the two power supplies and
Scenario 2: You have the following usage figures configured:
Power supply 1 = 2500 W
Additional Power supply 2 = 2200 W
Current Usage = 2000 W
Current mode = combined mode (so current capacity is 4400 W).
You decide to change the switch to redundant mode. Then the current capacity
decreases to 2200 W.
Reason: 2200 W is the lesser of the two power supplies.
Scenario 3: You have the following usage figures configured:
Power supply 1 = 2500 W
Additional Power supply 2 = 1800 W
Current Usage = 3000 W
Current mode = combined mode (so current capacity is 3600 W).
You decide to change the switch to redundant mode. Then the current capacity
decreases to 2500 W and the configuration is rejected.
Reason: 2500 W is less than the system usage (3000 W).
This table describes these scenarios.
OL-29291-02
Table 20: Combined Mode Power Supply Scenarios
Scenario Power Supply
1 (W)
1 2500
2 2500
3 2500
it is less than the system usage.
Configuration Guidelines for Power Supplies
Current Usage Insertion of
(W) Power Supply
2 (W)
2000 1800
2000 2200
2000 3300
Cisco MDS 9000 Family NX-OS Fundamentals Configuration Guide
New Capacity Action Taken
(W) by
3600 Power is never
shut down.
4400
The new
capacity is
5000
changed.
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