Research on fault tolerant paths and load balancing for storage area networks

To utilize the redundant paths in storage area networks, a storage path driver (SPD) is proposed and implemented to hook I/O requests bound for the logical units. The SPD driver routes all failed I/O requests on the failed path through survival paths. The failover time is reduced by skipping the retry operations of the disk device driver. I/O requests of the logical units are distributed among all physical paths, the host load is balanced on these parallel paths to improve the I/O performance, including increasing the I/O throughput and shortening the average I/O response time.