For a high-performance parallel machine to be a scalable system, it must also have a scalable parallel I/O system. This paper presents an experimental evaluation of the Intel Touchstone Delta's Concurrent File System (CFS). The main objective of the study is to determine the maximum file read/write rates for various configurations of I/O and compute nodes. In addition, we study the effects of file access modes, buffer sizes and file sizes on the system performance. In most cases, the result shows that performance of CFS scales as the number of disks is increased, but the sustained performance improvements are much lower than the system's peak capacity. We observe that the performance of CFS scales with the number of processors in the beginning, however, a plateu a quickly reached due to the I/O system bottleneck and enormous software overhead, especially that of synchronization. Finally we also show that the performance of the CFS can greatly vary for various data distributions commonly employed in scientific and engineering applications.