Benchmarking Private and Public Clouds

Earlier today I ran across a test that compared the performance of a private cloud against several public clouds.  The tests were done by CloudHarmony who appears to mostly focus on running tests against public clouds.  They have a variety of tests that seem to be pretty practical and reasonable measuring CPU, disk, memory, encryption, and something referred to as programming language performance (I thought this is what I was given grades for in CS class...).

According to their blog, CloudHarmony agreed to work with KT, a large Korean telecom and do some testing against their private cloud they had recently finished building.  CloudHarmony then compared the results against the many public clouds that they have tested.  In their conclusion they found that the KT private cloud performed very well in comparison to the public clouds.

I find this interesting as it a key aspect of what everybody is going to have to consider as they begin to adopt public clouds.  When does it make sense to use public vs private?  Performance is actually fairly easy to characterize if you can get meaningful tests.  More difficult will be understanding the costs and risks with doing either private or public clouds. I think that for many organizations, it will make sense to use both.  The organizations that get the mix of public and private right will have a competitive advantage, enabling their business to run more efficiently while maintaining agility.