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What happens when a single power suppy fails in a 2 power-supply configuration?

 
citpaj
Occasional Contributor

What happens when a single power suppy fails in a 2 power-supply configuration?

I'd like to know what happens to the other power supply when one of the two power supplies in a typical Proliant DL server fails.  Does the other power supply increase it's power consumption to compensate?  The reason I ask is that we are planning out a new rack, to include two PDU's connected to two separate power feeds.  It is our intention to have one power supply from each of our Proliants connected to one PDU, and the other power supply connected to the other PDU.  If one of the feeds was to fail, would that cause the remaining power supplies to put an additional load on the remaining good feed?  If this is the case, then it looks like we need to size each feed and PDU to accept the entire load (should one of the feeds fail).  Any comments would be much appreciated.  Thanks.

 

Paul.

 

2 REPLIES
Goutham_Sabala
Esteemed Contributor

Re: What happens when a single power suppy fails in a 2 power-supply configuration?

The second power supply is usually for redundancy , it depends upon the kind of power supply that you are using if it is a 750 400 or a 1000W PSU to decide on the load , I would advise you to go through the  HP Power advisor 

http://h18004.www1.hp.com/products/solutions/power/index.html

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Goutham Sabala
gregersenj
Honored Contributor

Re: What happens when a single power suppy fails in a 2 power-supply configuration?

yes, you must size your PDU's to handle full load.

 

In normal operation the load is distributed evenly on both/all PSU's.

In case of failure, the other PSU(s) will take the load from the failed PSU.

There's some exceptions to this, but rule is that each PDU must be able to handle full load.

 

Lets say

you've got a rack of servers, all with 2 PSU's, and 2 PDU's.

If you suffer from a power loss on one of the PDU's, the other PDU has to take the full load.

 

BR

/jag