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Redundant power supplies

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Ludo Marlisa
Occasional Visitor

Redundant power supplies

Hi Colleagues,

I read that, with both power buses active, each power supply will evenly share the server load.

Is there a way to address a primary and a secondary power supply? (software or hardware wise..)

I will explain why we would like to do this. In our data centre we pay a fixed price for the (first) power feed of 20A. we like to have a second power feed of 20A, but we cannot get a fixed price for this second feed. So I would only like to use it as a “fail over”.

Other question:

We are working on a project where we are planning to use several HP Proliant DL 360G6. Our plan is to place them in a data centre. In order to calculate the total power consumption of our rack, I will need to know the power consumption of a HP Proliant DL360G6.

Therefore I found the HP power calculator, but it doesn’t conclude the next generation servers (ML/DL generation G6).

Is there a other way to determine the current need for a DL360G6?

thank you for your responses.

Re: Redundant power supplies

The calculator gives the max used. The unit will use different amounts depending on how the settings are set and the requirements of the server. Best would be a meter and check the usages over a given time.
One option for the separate power would be to use a failover strip that runs from one circuit until it fails and then switches to the other. We have used this on some of the three and four power supply units.
rick jones
Honored Contributor

Re: Redundant power supplies

Not to further complicate life but... :) for the HP Blades, one can configure the blade chassis (through the onboard administrator) to have it fully load one PSU before starting to load another.

Whether or not this functionality might be included in any of the G6 rackmount servers I do not know, but it may be worth checking.

I will point-out that even if one can do that with the G6 rack mount servers, the "standby" PSUs will probably still be drawing at least a little power.

As for the power calculator not including the DL380 G6, are you certain you have an up-to-date power calculator? A web search of "DL380 G6 power calculator" found this:

which suggests there has been a migration to a new tool for the G6 and beyond servers.
there is no rest for the wicked yet the virtuous have no pillows
Glenn Matthys
Frequent Advisor

Re: Redundant power supplies

Redudant PSU's are connected in parallel so they will share the load 50-50. Redundant PSU's do carry an overhead though, about 20%. So if your server uses 1A with a single PSU, you can expect a power usage of 0,6A per PSU when using 2 redundant PSU's.

If you do not want to use power on your second feed, maybe an automatic transfer switch could be a solution for you.
Ludo Marlisa
Occasional Visitor

Re: Redundant power supplies

Hi Guys,

Thank you for you replies.

Two things:

@Jones: thanks. I had found the same link. When you continue following the links. You will find out that there exists an power calculator for the G6, but the last link (the one where you can actually download the calculator) doesn't work. Apparently there is an error on the page?!

@everyone: We found out that there are 4 "Redundant power supply modes" (see attached photo). We haven't tested it in the wild (yet), but I think we can reduce the consumption of the second power feed to a minimum.

Still remaining: the total consumption question... still hope to find an answer on this one...

Again thank you all for your answers.