Convergence Architecture. Not anticipated by its originators, commodity clusters and
Beowulf-class systems have evolved into what has become the de facto standard for parallel
computer structure, having converged on a communitywide system architecture. Since the
mid-1970s, the high-performance computing industry has dragged its small user and
customer base through a series of often-disparate parallel architecture types, requiring major
software rework across successive generations. These changes were often a consequence
of individual vendor decisions and resulted in low customer confidence and a strong reticence
to invest in porting codes to a system that could easily be obsolete before the task was
complete and incompatible with any future generation systems. Commodity clusters
employing communitywide message-passing libraries offer a common structure that crosses
vendor boundaries and system generations, ensuring software investment longevity and
providing customer confidence. Through the evolution of clusters, we have witnessed a true
convergence of parallel system architectures, providing a shared framework in which
hardware and software suppliers can develop products with the assurance of customer
acceptance and application developers can devise advanced user programs with the
confidence of continued support from vendors.
Price/Performance. No doubt the single most widely recognized attribute of Beowulf-class
cluster systems is their exceptional cost advantage compared with other parallel computers.
For many (but not all) user applications and workloads, Beowulf clusters exhibit a
performance-to-cost advantage of as much as an order of magnitude or more compared with
massively parallel processors (MPPs) and distributed shared-memory systems of equivalent
scale. Today, the cost of Beowulf hardware is approaching one dollar per peak megaflops
using consumer-grade computing nodes. The implication of this is far greater than merely the
means of saving a little money. It has caused a revolution in the application of
high-performance computing to a range of problems and users who would otherwise be
unable to work within the regime of supercomputing. It means that for the first time,
computing is playing a role in industry, commerce, and research unaided by such technology.
The low cost has made Beowulfs ideal for educational platforms, enabling the training in
parallel computing principles and practices of many more students than previously possible.
More students are now learning parallel programming on Beowulf-class systems than all
other types of parallel computer combined.
Flexibility of Configuration and Upgrade. Depending on their intended user and
application base, clusters can be assembled in a wide array of configurations, with very few
constraints imposed by commercial vendors. For those systems configured at the final site by
the intended administrators and users, a wide choice of components and structures is
available, making possible a broad range of systems. Where clusters are to be dedicated to
specific workloads or applications, the system structure can be optimized for the required
capabilities and capacities that best suit the nature of the problem being computed. As new
technologies emerge or additional financial resources are available, the flexibility with which
clusters are imbued is useful for upgrading existing systems with new component