Calculate Power Capacity in UCS 5108 chassis

[a.giorgi]

Hi everybody:

I'm looking for a tech paper that state the relationship between the PSU and Blades in a 5108 chassis

I want to resolve design questions like:

How many PSU I need if I have only 3 half size blades and I want redundancy N+1?

Or how many PSU I need to support 4 half size blades and I want grid redundancy?

I was looking for diferent pages like:

http://www.cisco.com/assets/cdc_content_elements/flash/dataCenter/cisco_ucs_power_calculator/

http://www.cisco.com/en/US/prod/collateral/ps10265/ps10280/UCS_Power_Supply_Configuration_and_Provisioning.pdf

with no success

Can anyone help me? I'll apreciate!

Thank you in advance

Alberto from Spain

[kg6itcraig]

Sorry it this is a bit of a "street' answer and not scientific.

You always need 4 PDU's or the chassis will constantly show errors. You want 0's across the top left of your screen and call home only reporting "real" majors and criticals or you don't know what is going on.

Each PSU is 14 amps, and can support a full chassis. You only need one, have tested that with a full chassis and servers blazing 100% cpu. Your power cord will get hot.

Have had power issue's with the PDU's and had to pull one at a time and re-seat to fix. I would always run 4 pdu's because UCS is only 2 years old or so and I don't think Cisco has the PDU/Chassis relationship 100% yet in the code. More is better.

On a last note you can see what a PDU or Chassis is pulling and graph it in UCSM. So there you go. You can even grab that via SNMP and Cacti it.

We run 4 circuits for each rack and plug each of the 4 PSU's into a different one. The UCS will balance the load perfectly across all 4.

Craig

[l.waldenberger]

sorry, but it depends on your power/psu policy if there are any errors, same page like the chassis discovering policy (amount of uplinks)...

but what craig said about the power consumption is right - i haven't seen a halfsize blade consuming more than 300W - but it isn't optimal - use two, if four are too expensive or you are not sure about it - we had the same constellation for about a half year.

[shirishd]

Hi ,

5108 Chassis comes with 4 power supply with n+n redundancy .Each power supply capacity is 2500W.

Each blade required 550W power so one power supply can provide power to 4 blades .

I have tested four blade by one power supply , believe me it was worked without any issues.

[a.giorgi]

Thank you very much to all of you!

Cheers

Al