[BBLISA] PDU Power Ratings?

[Dewey Sasser]

On 4/2/2014 4:51 PM, John P. Rouillard wrote:
> ...If that isn't done what happens if the P1 breaker trips? The 1/2 of
> the load being borne by P1 now is pulled from P2...

At one point I measured the power consumption of some HP DL380G5s at the 
plug (VM hosts that we kept around 75-90% CPU load but effectively no 
disk load).

Alas, I don't have the numbers any more but I recall that the power draw 
when running on a single supply was only incrementally more (25%?) than 
the power draw of each supply when both were operational. This results 
surprised me as I was expecting what John is expecting:  2x the load.

I also recall finding that the operational current -- even when 
operating around 75% CPU load on a single power supply -- was much less 
than the start-up current and IIRC the startup current would last for 
10s of seconds at boot.  (And neither had any resemblance to the 1000W 
spec on the power supplies.)

My conclusion was that the issue John points out wasn't actually an 
issue for me but that if I ever brought down the whole system (which I 
believe happened once due to building power issues), the power-on 
current draw could be an problem and that if I started pushing the 
circuits, stagger-start would be the order of the day.

G5s are outdated and I'm sure your equipment is very different from what 
I measured 4 or so years ago, but the take-away is:  go measure 
something, don't just go on spec.

In theory there's no difference between theory and practice.

--
Dewey