Scale-up vs. Scale-out: A Case Study by IBM using Nutch/Lucene

Scale-up solutions in the form of large SMPs have represented the mainstream of commercial computing for the past several years. The major server vendors continue to provide increasingly larger and more powerful machines. More recently, scale-out solutions, in the form of clusters of smaller machines, have gained increased acceptance for commercial computing.

Scale-out solutions are particularly effective in high-throughput web-centric applications.
In this paper, we investigate the behavior of two competing approaches to parallelism, scale-up and scale-out, in an emerging search application. Our conclusions show that a scale-out strategy can be the key to good performance even on a scale-up machine.

Furthermore, scale-out solutions offer better price/performance, although at an increase in management complexity.

Read more about scaling out/up and about the conclusions here (PDF - you can also download it)