Device and method for input/output control of a computer system for efficient prefetching of data based on lists of data read requests for different computers and time between access requests

An input/output control method in a system in which a plurality of slave devices and a storage device are connected to a mainframe electronic computer for executing data transaction between said storage device and said mainframe electronic computer, said method comprising:

• determining, when a data read request is generated from a slave device, whether a specified period of time has passed since generation of a previous data read request from the same slave device;
• adding data read requests generated within a specified period of time after generation of a previous data read request from the same slave device to the end of a list with data read requests from the slave device recorded in the order of generation of the data read requests;
• registering data read requests, each generated after passage of a specified period of time since generation of a previous data read request from the same slave device, at a header of a new list for recording therein data read requests from the same slave device in the order of generation of the data read requests;
• and
• transferring data to a cache memory by prefetching the data from said storage device based on the list.

A method of an input/output control device coupled to a computer, said method comprising:

• storing a list including data read requests from computers recorded therein according to an order of generation of the requests;
• determining whether to add a next data read request from one of the computers to the list corresponding to the one of the computers or to begin a new list, based upon whether the next data read request was made before a specified time had passed since the generation of a previous read request from the same computer;
• and
• prefetching data according to the list.

An apparatus comprising:

• a network;
• clients, coupled to the network, each client comprising a computer transmitting data read requests;
• a server, coupled to the network, comprising a computer, receiving the data read requests from the clients;
• a disk sub-system, coupled to the server, and comprising an input/output control device storing a list including the data read requests transmitted from the clients recorded therein according to an order of generation of the requests and determining whether to add a next data read request from one of the clients to the list corresponding to the one of the clients or to begin a new list, based upon whether the next data read request was made before a specified time had passed since the generation of a previous read request from the same client, said input/output control device prefetching data according to the list.