In this paper we propose a high performance parallel file system over iSCSI (iPVFS) for cluster computing. iPVFS provides a cost-effective solution for heterogeneous cluster environment by dividing a set of I/O servers into two groups, one group with higher performance servers as I/O nodes, while another group with relatively lower performance machines serves as storage target nodes. This combination provides a higher aggregate performance because of the cooperative cache among different target nodes. We have developed a model to analyze iPVFS. Our simulation results show that using same number of total nodes, iPVFS outperforms PVFS for both small requests and large requests under different workloads.