Abstract: An RDP device driver for UNIX and Windows NT operating systems is designed and implemented. By using a multi-layered device driver approach, an RDP driver on top of a disk device driver is implemented, and the problem of direct communication with disk hardwares is solved. To hook and process the disk I/O requests, RDP driver isolates the path failure and balances the I/O requests between paths. The I/O requests of the failure path is switched to the survival path, so the system is more reliable. The driver dispatches the I/O requests to multiple paths via three different algorithms, to increase the system’s I/O throughput capacity.