A data processing system includes compute nodes, at least one metadata server, iSCSI storage access servers, and data storage devices. The metadata server services requests from the compute nodes for file mapping information identifying iSCSI LUNs and logical blocks of file data. The storage access servers service iSCSI I/O requests from the compute nodes, and report server loading to the metadata server. A Gigabit Ethernet IP network transfers read and write data between the compute nodes and the storage access servers. The storage access servers are linked to the data storage devices for parallel access to iSCSI LUNs of the file data in the data storage devices. The metadata server is programmed for server load balancing by indicating to the compute nodes respective ones of the storage access servers that should be used for access to the iSCSI LUNs.