kelemvor33
3 Silver

PSU load balanacing on 620/630/640/etc servers? Active/Passive or Active/Active?

Hi,

We have a bunch of servers in our data center and got a power report that shows one of the Power distribution strips is using 16 Amps and the other is using 2 Amps.  We always plug in our servers so one PSU goes to each power strip.

I need to know if these servers split the power load between them during normal use or if they are setup so that one PSU does al lthe work and the second one is only there in case the first one fails.

I picked a random server and looked in OMSA and I did see that under the Power Management area, it shows me PS1 Current 1.6A and PS1 current 0.2A which leads me to believe they are in an Active/Passive type setup instead of Active/Active

Can anyone confirm if this is how they are by default and more importantly, is this a setting I can change somewhere?  We'd like them to be Active/Active to share the load between the PSUs and the power strips.

Thanks!

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2 Replies
Moderator
Moderator

Re: PSU load balanacing on 620/630/640/etc servers? Active/Passive or Active/Active?

Hello

Please send a private message with your service tag to ensure we have all appropriate information on your system.

Thanks

Daniel Mysinger
Dell EMC, Enterprise Engineer

Get support on Twitter @DellCaresPRO

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Re: PSU load balanacing on 620/630/640/etc servers? Active/Passive or Active/Active?

For PowerEdge servers with more than one PSU populated, you can confi€gure the power supply options such as redundancy policy, hot spare, and power factor correction.


Hot spare is a power supply feature that configures redundant PSU to turn off depending on actual server load.  This allows the remaining PSUs to operate at a higher efficiency.  Either PSU 1 or PSU 2 can be configured as the primary PSU.

After Hot Spare is enabled, PSUs can become active or go to sleep based on load.

So you are likely seeing this case as asymmetric electrical current sharing is enabled in this case.  One PSU is awake and provides the majority of the current, the other PSU is in sleep mode and provides a small amount of current.  This is often called 1 + 0 with two PSUs and hot spare enabled.

If you want 50-50 sharing of current, simply disable hot spare.  However, do note efficiency will be less.

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