Hot Spare Feature; Removing A Redundant Power Supply Unit - Dell W4X15 Owner's Manual

NOTE: If two PSUs are used, they must be of the same type and have the same maximum output
power.
NOTE: For AC PSUs, use only PSU with the Extended Power Performance (EPP) label on the back.
Mixing PSUs from previous generations of Dell PowerEdge servers can result in a PSU mismatch
condition or failure to turn on.

Hot spare feature

Your system supports the hot spare feature that significantly reduces the power overhead associated with
power supply unit (PSU) redundancy.
When the hot spare feature is enabled, one of the redundant PSUs is switched to the sleep state. The
active PSU supports 100 percent of the load, thus operating at higher efficiency. The PSU in the sleep
state monitors output voltage of the active PSU. If the output voltage of the active PSU drops, the PSU in
the sleep state returns to an active output state.
If having both PSUs active is more efficient than having one PSU in the sleep state, the active PSU can
also activate the sleeping PSU.
The default PSU settings are as follows:
• If the load on the active PSU is more than 50 percent, then the redundant PSU is switched to the
active state.
• If the load on the active PSU falls below 20 percent, then the redundant PSU is switched to the sleep
state.
You can configure the hot spare feature by using the iDRAC settings. For more information about iDRAC
settings, see the Integrated Dell Remote Access Controller User's Guide available at Dell.com/
idracmanuals.

Removing a redundant power supply unit

Prerequisites
CAUTION: Many repairs may only be done by a certified service technician. You should only
perform troubleshooting and simple repairs as authorized in your product documentation, or as
directed by the online or telephone service and support team. Damage due to servicing that is
not authorized by Dell is not covered by your warranty. Read and follow the safety instructions
that are shipped with your product.
CAUTION: The system requires one power supply unit (PSU) for normal operation. On power-
redundant systems, remove and replace only one PSU at a time in a system that is powered on.
1. Follow the safety guidelines listed in the Safety instructions section.
2. Disconnect the power cable from the power source.
3. Disconnect the power cable from the PSU and remove the straps that bundle and secure the system
cables.
4. Unlatch and lift the optional cable management arm if it interferes with PSU removal. For
information about the cable management arm, see the systems rack documentation at Dell.com/
poweredgemanuals.
Steps
Press the release latch and pull the PSU out of the chassis.
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