R440 reboots when UPS switches to battery power

Question

Hello,

I have an R440 with two PSU both connected to a OR2200LCDRT2U UPS. When the UPS switches to battery power the R440 reboots. The R440 turns back on and works on UPS battery power, but there is the reboot at the time the UPS switches.

The other devices connected to the same UPS (i.e. a switch and a modem stay on and do not reboot).

For troubleshooting purposes I have tried to connect to the same UPS an older R420 (instead of the R440), and this does not reboot (i.e. stays on) when the UPS switches to battery power.

Could you please advise if there is any setting on the R440 that can be adjusted to prevent this behavior?

DELL-Charles R · Answer

Hello,

This could possibly be caused by UPS waveform type: Many line-interactive UPS models (like the OR2200LCDRT2U) output a simulated sine wave when on battery. Dell PowerEdge servers with high-efficiency PSUs often require a pure sine wave during transfer. If the waveform is not pure sine, the PSU may briefly lose sync and trigger a reboot.

Example: simulated sine wave or pure sine wave

https://www.dell.com/community/en/conversations/poweredge-hardware-general/poweredge-r440-apc-ups-problem/647fa339f4ccf8a8de909a0c?commentId=647fa3c3f4ccf8a8de9beae0

Why R420 works but R440 doesn’t may be because the older servers (like R420) have less sensitive PSUs and tolerate simulated sine wave and longer transfer times. R440’s PSU design expects enterprise-grade UPS with true sine wave output and fast transfer (<4 ms).

My recommendations to check would be:

Check if the OR2200LCDRT2U UPS has firmware update available
Check that the R440 firmware is up to date: BIOS, iDRAC and PSU firmware..

R440 Drivers and Downloads
https://www.dell.com/support/product-details/en-us/product/poweredge-r440/drivers

Use UPS with pure sine wave output and <4 ms transfer time.
Consider dual UPS configuration so you can put each PSU on different UPS for redundancy.

DELL-Rey G · Answer

I have seen variations of this over the years, and its a combination of the PSU tolerances and the UPS's wave forms (jagged,smooth), signal amplitude and timing. you could try playing with the Power Configuration settings in the idrac gui, but I dont see them making much difference. As a test, try leaving one PSU connected to a non-UPS power outlet

Rey
#Iwork4dell

JSa1987 · Answer

@DELL-Rey G​ I will try with one PSU connected to a non-UPS outlet. But it eludes me how this would help… would the hope be that the non-UPS outlet could somehow keep the server running in the moment when the UPS is switching to battery power even if the UPS has already detected an outage?

DELL-Rey G · Answer

kinda-sorta, just a test. I think there is a 'notification' to the system that something happened to the power flow and it reacts differently. #Iwork4Dell

PowerEdge Hardware General

R440 reboots when UPS switches to battery power

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