by lpar id 0 450 and lpar id 2 are excluded for access priority is given to the data access from the application 1 no matter which os is 0056 fig1 shows exemplary exclusion priority control tables for use in embodiment 3 of the present invention because accessibility judgment is also made by exclusion priority control per application in embodiment 3 one additional table is used more than the corresponding table shown in fig6 reference numeral 1625 a denotes an exemplary exclusion priority control table wwn lpar relation and this type of table corresponds to the exclusion priority control table 500 shown in fig6 reference numeral 1625 b denotes an exemplary exclusion priority control table wwn apl relation for each apl and wwn combination among apls 1720 to 1735 for wwns 1700 to 1715 whether the logical volume for example 0 is accessible by exclusion priority control is specified in this table 0057 fig1 shows an exemplary structure of a data frame for use in embodiment 3 of the present invention this data frame structure is basically the same as shown in fig3 except that an apl id 395 field to contain an application id is added to the payload 315 0058 fig2 shows an exemplary control frame for use in embodiment 3 of the present invention this control frame structure is basically the same as shown in fig7 except that an apl id 670 data field to contain an application id is added to the message 620 part according to embodiment 3 illustrated in fig1 exclusion priority control among applications running under different oss can be performed in the same manner as illustrated in the flowcharts of control exclusion control processing in fig1 and 14 in accordance with the present invention when one of a plurality of oss.