Hot Spare Feature; Removing An Ac Power Supply Unit - Dell PowerEdge R930 Owner's Manual

NOTE: When two identical PSUs are installed, the PSU configuration can be set to redundant (1 + 1) mode. In redundant mode,
power is supplied to the system equally from both PSUs to maximize efficiency.
NOTE: When only one PSU is installed, the PSU configuration is non-redundant (1 + 0). Power is supplied to the system only by
the single PSU.
NOTE: When four identical PSUs are installed, the PSU configuration can be set to redundant (2+2 or 3+1) mode. In redundant
mode, power is supplied to the system equally from all PSUs to maximize efficiency.
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 servers can result in a PSU mismatch condition or failure to power 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 an AC 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 needs 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.
NOTE: You may have to unlatch and lift the optional cable management arm if it interferes with the power supply unit (PSU)
removal. For information about the cable management arm, see the system's rack documentation.
Steps
1 Disconnect the power cable from the power source and from the PSU you intend to remove, and then remove the cables from the
strap.
2 Press the release latch and slide the PSU out of the chassis by using the PSU handle.
144 Installing and removing system components