INFORMATION PROCESSING SYSTEM, DATA STORAGE SYSTEM AND ITS CONTROL METHOD, AND DATA MULTIPLEXER

摘要

PROBLEM TO BE SOLVED: To realize an inhibition of a update Write request synchronized between multi external memory control units without sequence control in a host unit. SOLUTION: Utility pair is set by connecting multi main-side external storage control systems 2, 13 and 21 in a ring shape which are connected to a main-side host 1 through the medium of interface cables 30, 31 and 32. By a request issued from the main-side host 1 to the main-side external storage control systems 2, the Write inhibition is set to a logical volume under the main-side external storage control systems 2. The same command to the Utility pair is issued to the main-side external storage control systems 13 and 21, whereby a Write inhibition is set to the other main-side external storage control systems. By answering command completion in inverse order, i.e., from the main-side external storage control systems 2 to the main-side host 1, synchronized Write inhibition is implemented.