US Patent 7136970 Storage system and dynamic load management method thereof

A storage system accesses a storage device according to the host I/O request and internal I/O request for preventing a time out error of the host I/O due to a stagnation of command processing. The command processing section performs system load management, where the host I/O requests which are not managed by the storage system are managed according to the system load of the storage system, and for the host I/O requests which exceed the system load, the host I/O request is not processed but an error is replied, and the host retries the command to suppress the stagnation of command processing in the system.