BladeSystem Management Software

Power cap when Onboard Administrator is offline

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Power cap when Onboard Administrator is offline

Ed had a question from a customer about Power Capping on BladeSystem:



If a customer has an enclosure power cap set for a certain value, but then the OA's go offline for whatever reason, what happens to that power cap?  Does it go away?  Is it enforced?  I know each blade has a PMC, but is there any other way to view power consumption as a whole?


Ken and David replied:



Not 100% sure, but this is my understanding. 

The OA works by setting sub-caps on each ILO, and adjusting them up or down as workloads change.  If the OA is offline, the caps are still in place and enforced by the ILOs, but the enclosure can’t react to changes in workload to redistribute the sub-caps.


This is one reason that enclosure power capping requires redundant OAs…While not impossible, it is highly unlikely that both OAs would go ‘offline’ as far as the enclosure is concerned (which is different than being off the network). 



Thanks for the info guys. Any other comments or suggestions?