A "power supply redundancy lost" alert means the server is now running on fewer power supplies than its redundancy policy needs. It keeps running, but one more power problem can take it down. HPE's iLO guide names the most common reason: a loss of input power to a power supply, such as a brownout or an unplugged cord. A failed PSU, a mismatched replacement and a configuration that never met the redundancy requirement are the other documented causes. This guide covers how to tell them apart on Dell and HPE servers.
Before you start
- Record the alert, the PSU bay number and the time from the iDRAC Lifecycle Log or the iLO IML.
- Know how the server is cabled: which PSU goes to which PDU, UPS or circuit.
- If you may replace a PSU, have one with the same part number, rating and label as the one that stays in the server.
Warning: While redundancy is lost, the server depends on a single PSU. Dell's R760 manual states that the system requires one PSU for normal operation and that on power-redundant systems you remove and replace only one PSU at a time in a running system. Never unplug or pull the working PSU, and do not disconnect a PSU while its firmware is updating. Make sure workloads are protected and back up first.
Step 1 — Read the PSU status
- Dell iDRAC9: System > Overview > Power shows the PSUs;
racadm getsensorinfolists the status of each power supply among the system sensors. The redundancy policy is under Configuration > Power Management > Power Configuration. - HPE iLO 6: Power & Thermal > Power. The Power Supply Summary shows Power Status: Redundant; Not Redundant (at least one PSU is not providing power, most often because of lost input power); Failed Redundant (on four-PSU servers, fewer PSUs than required for operation); OK; or N/A. The Power Supplies list gives each bay's status, such as Good, In Use; Good, Standby; Input Voltage Lost; General Failure; or Mismatched Power Supplies, and whether the bay supports hot-plug.
iLO also reports Not Redundant when several PSUs are connected to the same iPDU, because losing that iPDU would cut all power.
Step 2 — Match the alert to its cause
| Alert | Meaning and action |
|---|---|
| Dell RDU0012 "Power supply redundancy is lost." (Critical) | The system was redundant and now is not, because of a PSU exception or an inventory change. Check the event log for PSU failures and review configuration and power consumption. |
| Dell RDU0014 "The power supplies are not redundant." (Informational) | The PSU configuration does not meet the platform requirements for redundancy; if a PSU fails the system may shut down. |
| Dell PSU0003 "The Power Supply Unit (PSU) ... is not receiving input power because of issues in PSU or cable connections." | Check that the input source is connected, power is within the PSU's requirements and cables are properly connected; then reseat or swap the PSUs. |
| Dell PSU0001 "Power supply ... failed." | Remove and reinstall the PSU; if it persists, collect a SupportAssist collection. |
| Dell PSU0006 / PSU0076 | PSU incorrectly configured / wattage mismatch. PSUs should have the same input type, feature set and power rating. |
| HPE "System power supplies are not redundant" (class 0x000b, code 0x0036) | Causes include a PSU not fully seated, AC power unavailable, a failed PSU, insufficient power for the installed hardware, or incompatible redundant PSUs. Check connections and PSU LEDs, check the power source, then replace the PSU. |
Step 3 — Check the input power first
- Check the power cord at both ends and the cable strap on the PSU handle.
- Check the PDU outlet, circuit breaker and UPS feeding that PSU. Plugging a known working device into the same outlet is a quick test.
- Make sure the two PSUs are fed from different sources if your design calls for grid redundancy, and that the input voltage suits the PSU. Dell notes that Titanium PSUs support only 240 V, and that two identical PSUs receiving different input voltages can output different wattages and trigger a mismatch.
- If the alert followed new hardware, HPE's guidance is to confirm the PSUs can carry the configuration; remove the new component and see if the issue clears.
For general room power design, see server room power, cooling and UPS basics.
Step 4 — Read the PSU and front panel LEDs
| Indicator | Documented meaning |
|---|---|
| Dell PSU: green | Valid power source connected and PSU operational |
| Dell PSU: blinking amber | Issue with the PSU |
| Dell PSU: not powered on | Power is not connected to the PSU |
| Dell PSU: blinking green | PSU firmware is updating; do not disconnect |
| Dell PSU: blinks green five times, then off (on hot-plug) | PSU mismatch (efficiency, feature set, health status or supported voltage) |
| HPE rear PSU LED: off / solid green | System is off or PSU has failed / normal |
| HPE Systems Insight Display power supply LED amber, health LED amber, power LED green | Redundant PSU installed but only one functional, AC cord not plugged into the redundant PSU, redundant PSU fault, or PSU mismatch |
Step 5 — Mismatched PSUs
- Dell: both PSUs must be the same type with the same maximum output and the same label type (for example EPP); mixing PSUs from previous PowerEdge generations is not supported. To correct a mismatch, replace the PSU with the blinking indicator; Dell cautions that swapping PSUs to make a matched pair can cause an error and an unexpected shutdown.
- HPE: mixing PSU types can limit or disable features, including power redundancy, and can make the system unstable. All PSUs should have the same output and efficiency ratings, the same part number and the same label colour. iLO shows a Degraded power supply status when mismatched PSUs are installed.
Step 6 — Replace a failed PSU
On the R760: disconnect the power cable from the outlet and from the failed PSU, free the cable from the strap, press the release latch and slide the PSU out. Slide the new PSU in until the latch clicks, connect the power cable and secure it with the strap, then wait about 15 seconds for the system to recognise it. Dell notes the new hot-swapped PSU is updated to the same firmware and configuration as the replaced one after the next server boot. On HPE servers, iLO's Hotplug column tells you whether a bay can be replaced with the server on; HPE says this is possible when the value is Yes and the PSUs are redundant.
Afterwards, confirm iDRAC logs the return to redundancy (Dell RDU0011 "The power supplies are redundant.") or iLO shows Redundant.
Redundancy settings
Dell's Power Configuration page holds the Power Redundancy Policy and Hot Spare. With Hot Spare enabled, one PSU sleeps and the other carries most of the load; Dell notes that if all PSU-1s are on one circuit and all PSU-2s on another, the second circuit carries much less load and can trigger warnings. On HPE Gen11, System Configuration > BIOS/Platform Configuration (RBSU) > Power and Performance Options > Advanced Power Options > Redundant Power Supply Mode chooses Balanced or a High Efficiency mode (it requires Workload Profile set to Custom). HPE states High Efficiency Mode does not affect power redundancy.
Escalate to vendor support when a new PSU also reports a fault, when a PSU fails again soon after replacement, or when power alerts appear together with system board errors. Check warranty status first (see checking Dell and HPE warranty).
Checklist
- Alert, PSU bay and time recorded; PSU status read in iDRAC or iLO.
- Cord, PDU outlet, breaker and UPS checked for the affected PSU.
- PSU LEDs read; mismatch ruled out (same part number, rating and label).
- Only the faulty PSU removed; working PSU never touched.
- Redundancy restored and confirmed in the logs.
- Case opened if the replacement also faults.
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