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February 16th, 2018 08:00

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!

Moderator

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6.2K Posts

February 16th, 2018 10:00

Hello

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

Thanks

March 22nd, 2018 09:00

For PowerEdge servers with more than one PSU populated, you can configure 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.

1 Message

November 14th, 2019 11:00

I bought a Poweredge T640 from Dell outlet and it only had 1 power supply and I want to add an additional 2nd power supply. The current power supply is a Model E495e-s1 (94% efficiency) and has a dp/n ovkdd2 which I can not find.

My service tag is

 Thank you,

Kirk

 

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