@Article{thakur:applications, author = {Rajeev Thakur and Ewing Lusk and William Gropp}, title = {{I/O} in Parallel Applications: The Weakest Link}, journal = {The International Journal of High Performance Computing Applications}, year = {1998}, month = {Winter}, volume = {12}, number = {4}, pages = {389--395}, note = {In a Special Issue on I/O in Parallel Applications}, URL = {http://www.mcs.anl.gov/~thakur/papers/ijsa-article.ps}, keywords = {parallel I/O application, pario-bib}, abstract = {Parallel computers are increasingly being used to run large-scale applications that also have huge I/O requirements. However, many applications obtain poor I/O performance on modern parallel machines. This special issue of IJSA contains papers that describe the I/O requirements and the techniques used to perform I/O in real parallel applications. We first explain how the I/O application program interface (API) plays a critical role in enabling such applications to achieve high I/O performance. We describe how the commonly used Unix I/O interface is inappropriate for parallel I/O and how an explicitly parallel API with support for collective I/O can help the underlying I/O hardware and software perform I/O efficiently. We then describe MPI-IO, a recently defined, standard, portable API specifically designed for high-performance parallel I/O. We conclude with an overview of the papers in this special issue.} }