Clusters are the most common solutions for high performance computing at the present time. In this kind of systems, an important challenge is the I/O subsystem design. Typically, these environments are not flexible enough and the only way to solve performance bottlenecks is adding new hardware. In this paper, we show how an I/O proxybased architecture can improve the I/O performance of cluster applications in three ways: adapting to the application requirements, reducing the load on the I/O nodes, and finally, increasing the global performance of the storage system. 1