Understanding 'Not Redundant' power

[chuckk281]

Steve had a question on the Blade Chassi power supply redundancy.

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All,

I have a customer with 90 C7000 enclosures all fully loaded with 6 PSUs. While checking some show all output I spotted that all but one enclosure is running with ‘Not Redundant’ power mode. All enclosures are drawing less than half the available DC power. They are using 3 psu’s on one rack PDU and the other three on another PDU (with each PDU connected to a different breaker).

My question is – in ‘Not Redundant’ will the loss of a single PSU cause the enclosure to shutdown? How about the loss of three PSU’s (ie one rack PDU or a breaker)? In both scenarios there is sufficient power available but does not using a ‘Redundant N+N’ power mode stop that power being available.

Hope that makes sense.

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Monty joined the discussion:

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HP c-Class BladeSystem has a single power domain in both the c7000 and c3000 enclosures – please see the c7000 or c3000 enclosure tech briefs for the description.

All installed power supplies that have active AC input (or active DC input in the case of the DC power supplies) are available to share the task of delivering the output power to the power backplane (actually bus plates – not a circuit board).

The purpose of configuring the Power Mode on the OA is to inform the OA of the customer intention on input power redundancy, and the OA uses the Power Mode to calculate the Power Capacity of the enclosure where:

• AC Redundant (N+N) – OA will set enclosure Power Capacity equal to the combined max output power of N (half) the installed power supplies
• Power Supply Redundant (N+1) – OA will set the enclosure Power Capacity equal to the combined max output power of N installed power supplies
• Not Redundant (N) – OA will set the enclosure Power Capacity equal to the combined max output power of N (all) installed power supplies

The implication of setting Power Mode = Not Redundant IF the customer intention with the wiring described is to protect against loss of one AC ‘side’, is that the OA will have allowed power allocations to exceed the ability of half the power supplies and the enclosure is exposed to brownout if one side of the AC inputs is lost.

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Any other comments or suggestions?