UCS 5108 Chassis Power Balancing N+1 & GRID

I am trying to figure this out and VALIDATE.

Created a post about this over at community.cisco.com
https://community.cisco.com/t5/unified-computing-system-discussions/ucs-5108-chassis-n-1-and-grid-and-pdu-cabling/m-p/5263593#M36311

This article from 2018 is great stuff. Need to do some testing to validate PSU’s behave the way documented.

I think this article is correct, would like to confirm.

Cisco UCS 5108 Chassis Power Policy Options and Redundancy Demystify
https://icookservers.blog/2018/04/05/cisco-ucs-5108-chassis-power-policy-options-and-redundancy-demystify/

The article has a gist of:
N+1 is for a PSU failure.
GRID is for a PDU failure.

Are the PSU ON/OFF modes below correct? 
GRID seems to be the way to go for 2 or 4 PDU’s.

PDU Cabling would be like this:
PDU-A = PSU1
PDU-A = PSU2
PDU-B = PSU3
PDU-B = PSU4

GRID Mode with (Option 1)
PSU1/PSU2 to A
PSU3/PSU4 to B

If a PDU fails – You are saved!

PSU1 – A ON
PSU2 – A OFF (Power Saving Mode)
PSU3 – B ON
PSU4 – B OFF (Power Saving Mode)

Thanks in advance for any enlightenment on 5108 Chassis Power.

N+1—The total number of PSUs to satisfy non-redundancy, plus one additional PSU for redundancy, are turned on and equally share the power load for the chassis. If any additional PSUs are installed, Cisco UCS Manager sets them to a “turned-off” state. If the power to any PSU is disrupted, Cisco UCS Manager can recover without an interruption in service.

In general, a Cisco UCS chassis requires at least three PSUs for N+1 operation.

Grid—Two power sources are turned on, or the chassis requires greater than N+1 redundancy. If one source fails (which causes a loss of power to one or two PSUs), the surviving PSUs on the other power circuit continue to provide power to the chassis.

This guy has an eclectic take on cabling the PSU’s are well, and syncs with the above article.

Power cable considerations on the UCS Mini
https://www.jpaul.me/2015/02/power-cable-considerations-on-the-ucs-mini/comment-page-1/?unapproved=753123&moderation-hash=2e81fc645d4987d7dec802eb4bae06fd#comment-753123

An uncertainty I have is newer code levels than referenced in the above articles. Also not sure if UCS Mini is even still around. 2018 is 1000 years ago in computer hardware years.

Will update with more findings along the way.

 

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2/24/2025 Update

Got a reply from a Cisco Employee on the forum!!!

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