Power Efficiency of HP Rack Mount vs. Blade Servers, 3.5% difference in performance/watt

Burton Group has a blog entry discussing the comparison of HP rack and blade servers.

Power Efficiency – Rack Mount vs. Blade Servers

HP has just published SPECpower_ssj2008 results for a c7000 blade system, the results when compared to existing rack mount server results for the same benchmark make interesting reading. Before I say anything else, kudos to HP for publishing a power benchmark on blades, now if we can only get IBM, Dell, Cisco etc to follow suit.

The blade system used sixteen identically configured blades to achieve the following result:

ssj_ops @ 100%
avg. watts @ 100%
avg. watts @ idle


Each of the 16 blades used a pair of Intel Xeon 5520 processors and 8 GBs of memory. The result is interesting because HP just happens to have published results for an identically configured Proliant DL 380 G6 rack mount server. I’ve multiplied the rack mount result by 16 so we can directly compare power efficiency:

ssj_ops @ 100%
avg. watts @ 100%
avg. watts @ idle


From these results we can draw some useful conclusions:

  • There is a difference of roughly 3.5% for performance/watt, with blades holding the advantage.
  • Idle power consumption for the blade solution is approximately 25% lower
  • Peak power consumption for the rack mount solution is approximately 2% lower

The writer makes the statement the 3.5% difference in performance per watt is not significant, but he assumed the blade enclosure was fully populated with 16 blades.  How many blade enclosures do you see fully populated? 

Maybe the rack mount servers are more energy efficiency in most circumstances.

As the author says it would be great if we could get the same data from IBM, Dell, and Cisco.  But, then people wouldn’t be buying the blade enclosures.