...Here is where some of the largest potential pitfalls lie. From a technology perspective, most companies have implementedserver virtualization to varying degrees, and in some ways, a cloud model can be viewed as a large-scale expansion...
http://www.ecommercetimes.com/rsstory/66990.html
...load balancer exposes a single virtual instance of a server identity while supporting multiple instances of the implementedserver. The load balancer abstraction layer then provides additional value by distributing the load for the virtual service...
http://www.findwhitepapers.com/whitepaper356/