Following on from my first post I'll take a look at the affect hardware configuration will have on the power consumption of the enclosure.

To do this I went into the Blade Power Sizer and configured up two equivalent systems. I kept the enclosure configuration constant with just 2 x Virtual Connect 1/10 Ethernet Modules and 2 x Virtual Connect Fibre Modules just to simplify the example.

The Blade configuration was BL460cG1, 2 x 2.66GHz CPUs, 16GB RAM, 2x 1Gbit Ethernet, 2x 4Gbit Fibre Channel, 2x 72GB 10K SAS Drives.

Why did I pick BL460cG1, to be honest the actual server doesn't matter, what I'm trying to show here is that the hardware configuration can have a very significant effect on the enclosure power consumption.  The nice thing about the BL460cG1 for this purpose is that it shows this really clearly.

The difference between the two configurations is 798W at idle and 1,617W at high load, which is a huge difference.

Where is most of the power difference coming from, well there are 3 differences in the configuration:

1. CPU - E5450 (80W TDP) versus L5450 (50W TDP)
2. Memory - 8 x 2GB FB-DIMMs versus 4 x 4GB Low Power FB-DIMMs
3. Power Supply - HP 2250W versus HP 2400W High Efficiency

The power supply is worth about 200W (25%) at Idle and 300W (18%) at full load on this configuration. So it's a significant proportion of the difference at the idle load.  At the high loads, though, the majority of the difference between the two configurations is coming from the CPU and Memory.  A standard FB-DIMM takes approximately 10W per DIMM so the difference between 4 and 8 physical DIMMs is roughly 40W per server, additionally a Low Power DIMM uses 2W - 3W less than a standard DIMM.

So what can I take from this example? 

• System configuration matters. A lot.
• At high loads the server power consumption is the main factor
• At low server loads the enclosure becomes a larger proportion of power consumption.

 What are the practical steps I can use to reduce power consumption.

• Use the lowest power cost effective processor
• Use smallest number of largest physical DIMMs that are practical and cost effective.
• Use the highest efficiency power supply that is available

Comments as always are welcome. Let me know where you want me to go as I continue on with this series.

Part 2 of this series is Applications Matter