Storage control apparatus

A computer system constituted by at least two mainframe host;

• at least one open system host;
• and a disk system having a frame independent from those of said mainframe hosts and said open system host, and storing thereinto data which is accessed by said mainframe host and second open system host, wherein:
• said disk system comprises means including a fixed length format interface for connecting said mainframe hosts and said open system host thereto;
• said open system host comprises means including a fixed length format interface for connecting said disk system thereto;
• each of said mainframe hosts comprised a plurality of processors and a main memory;
• at least one processor among said plurality of processors comprises means for storing into said main memory, a read/write request issued in accordance with a variable length format;
• at least one processor among said plurality of processors comprises:
• means for converting the read/write request issued in accordance with the variable length format into a fixed length format in accordance with a variable length format/fixed length format conversion function;
• and further for executing the converted read/write request;
• means for storing partial data of said disk system into said main memory;
• means for notifying that which data is updated by a write request to another mainframe host when the write request issued in accordance with the variable length format is processed;
• means for receiving from another mainframe host information as to which data is updated by the write request, and thereby erasing data to be updated from said main memory;
• and
• means for connecting said disk system thereto by the fixed length format interface.