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TonyWil
What's DOS?
Posts: 2
Registered: ‎08-05-2019
Location: US
Views: 270
Message 1 of 5

Why do I need a 1600W Power Supply for a SR950?

We have a New SR950 that has 8 Xeon SP Gen2 processors and 96 DDR4 64GB DIMMs and 4 x 1100-watt Platinum Plus power supplies. The power supplies are configured for N+N redundancy. When we either Boot the server or remove a PS for testing we get an alert that the processors are operating in a Degraded State.

 

In talking with Lenovo Support the conclusion seems to be that we need 4 x 1600-watt power supplies. My question is why do we need them? When we look at power consumption in XCC it looks like the max power consumption is 2600 watts and we are using aproximately 1100 watts. We never seem to go above 1600 watts consumed. Even with two 1100-watt PSs that should be 2200-watts and more than enough to powe the server.

 

How is the server calculating that there is not enough power?

Lenovo Employee Dannyhsueh
Lenovo Employee
Posts: 227
Registered: ‎08-05-2018
Location: US
Views: 246
Message 2 of 5

Re: Why do I need a 1600W Power Supply for a SR950?

Hi Tony

 

You can use Lenovo Capacity Planner (LCP) to calculate power consumption and levels of current in different deployments. Please refer the KB - How to plan the power distribution of a server rack  for more detail information. 

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Lenovo Employee RyanTsai
Lenovo Employee
Posts: 254
Registered: ‎03-06-2017
Location: TW
Views: 226
Message 3 of 5

Re: Why do I need a 1600W Power Supply for a SR950?

Hi TonyWil

 

Not only the processor and memory will consume power, adapter cards and internal storage devices and fans should also be considered.

When the system is running at full speed, the power consumption of all devices will increase.

 

As Dannyhsueh said, you can use Lenovo Capacity Planner to calculate power consumption. I tried to set LCP deployment according to the processors and memory configuration you provided, without extra devices. When loading is 100%, only set up 4x 1600 watt PSU to N + N redundancy with oversubscription. And that will not exceed the power utilization.

 

http://download.lenovo.com/servers/lnvgy_sw_capacityplanner_v1.8.7_anyos_32-64/start.html

 

LCP.png

Please feel free to leave your comment, thank you for support Lenovo
TonyWil
What's DOS?
Posts: 2
Registered: ‎08-05-2019
Location: US
Views: 205
Message 4 of 5

Re: Why do I need a 1600W Power Supply for a SR950?

Hi RyanTsai,

 

Thank you and Dannyhsueh for pointing me towards LCP. It's a very good tool. I think I see where things went wrong. If you configure for N+N redundancy with 1100W PSUs LCP throws an exception. If you configure with no redundancy LCP accepts the configuration. The power consumption for our server exceeds the capacity of two 1100W PSUs so in a N+N configuration there would not be enough power.

Lenovo Employee RyanTsai
Lenovo Employee
Posts: 254
Registered: ‎03-06-2017
Location: TW
Views: 194
Message 5 of 5

Re: Why do I need a 1600W Power Supply for a SR950?

Hi TonyWil

 

Glad to help Smiley Happy

Please feel free to leave your comment, thank you for support Lenovo

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