The redundant power supply in the server supports concurrent maintenance, which enables you to remove and replace a power supply without shutting down the server, if the other power supply is online and working.

The server supports model A271 and A271a (1400 watt) power supplies. The power supply (PS) provides conversion from the AC lines to the system, accepting 220 volts AC (VAC) only. The PSUs are hot-pluggable, and in most cases provide fully redundant “1+1” power, allowing the system to suffer the loss of a PS or an AC feed with no loss to system availability.

In maximally configured systems, it is possible that the worst-case power consumption of the system could exceed the capacity of a single power supply. Power supplies provide an over-subscription mode (always enabled), which allows the system to operate with fault-tolerance, even with modest excursions beyond the rated capacity of a single PS. This over-subscription support is accomplished using hardware signaling between the PS and motherboard circuitry, which can force the system to throttle processor (CPU) and memory power in the event that a power supply is lost. The resulting power savings is enough to allow the system to continue to run (in a lower-performance state) until the power problem is resolved.

If a power supply fails and you do not have a replacement available, leave the failed power supply installed to ensure proper airflow in the server.

The following status indicators (LEDs) are lit when a power supply fault is detected:

• Front and back panel Fault-Service Required LEDs

• Rear Power Supply Fault-Service Required LED located on the server front panel

• Amber Fault-Service Required LED on the faulty power supply

For more information, see Power Supply Status Indicators.