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2 Intern
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374 Posts
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3333
January 2nd, 2018 11:00
Why would a server reboot after losing one power supply?
One of our data centers had a power issue over the weekend that affected one of our UPS devices. OMSA shows that input power to PSU2 was lost but PSU1 was fine.
However, the servers all rebooted themselves. These are Poweredge R430s running Server 2016.
Anyone have any idea why a server would reboot after losing one, but not both, power supplies?
Windows Event Viewer only shows an Unexpected Shutdown but no reason for it.
I'm at a loss. Thanks.
UPDATE: Is it possible that both PSUs lost power but when the 2nd one dropped, it couldn't record anything because there was no power left? However, maybe the 2nd drop was just a blip for a split second and that the power then came back on automatically? If so, would the server have rebooted on its own if BIOS isn't set that way? Or is BIOS set that way by default? I'll have to double check that but we don't change any BIOS settings on our servers.
Daniel My
12 Elder
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6.2K Posts
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January 2nd, 2018 14:00
Hello
If all power to the system is unexpectedly lost then you cannot trust the log errors that occur at the time of power loss. Some errors may not be reported, like PSU 1 losing power, and erroneous may be reported.
As long as the PSUs are in a redundant configuration with the same output wattage they should fail-over without shutting the system down in the event of a single PSU power failure.
Thanks
kelemvor33
2 Intern
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374 Posts
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January 2nd, 2018 18:00
Yeah, I did a quick test on a spare server. If I pull one power cord and then pull the other power cord, the OMSA/iDrac logs don't record that the 2nd one lost power since it didn't have power to write to the logs I guess. When the server boots back up it just says an unexpected shutdown as our only clue.