Design and Implementation of an RDP Device Driver for Windows 2000

A redundant data path(RDP) device driver for Windows 2000 is proposed and implemented to provide automatic transparent failover and load balancing across multiple SCSI or fibre paths between the hosts and the storage subsystems. RDP driver is implemented as a filter driver on top of the traditional disk device driver, it is completely transparent to the upper file system and the lower level physical device. I/O requests bound for the disk device are routed first to the RDP driver, then RDP driver calls the disk driver to perform these I/O requests. RDP detects the path failure and reroutes all subsequent I/O traffic through survival paths. I/O requests are distributed to different physical paths to achieve the maximum throughput. The multi layered device driver approach significantly reduces the implementation overhead and improves portability, and does not require any changes to the OS or the on disk data layout. RDP driver keeps applications running under path fault conditions and improves disk I/O performance.