1. A computer system comprising: a first storage system having a plurality of first storage areas capable of storing data used by a first host computer via a first communication line, a first control portion connected with a plurality of disk units forming the first storage areas, and a first memory connected with the first control portion; a second storage system having a plurality of second storage areas capable of storing data used by a second host computer via a second communication line and a second control portion connected with disk units forming the second storage areas, the second storage system being connected with the first storage system via a third communication line; a third storage system connected with the first storage system via a fourth communication line, having a plurality of third storage areas for storing copy of data stored in the first storage areas of the first storage system; and a fourth storage system connected with the second storage system via a fifth communication line and with the third storage system via a sixth communication line, having a plurality of fourth storage areas for storing copy of data stored in the second storage areas of the second storage system, wherein the first control portion controls access from the first host computer to the data stored in the first storage areas and transmission of the copy of data stored in the first storage areas to the third storage system via the fourth communication line, in which the first and the third storage areas are formed as a first pair relation, wherein the second control portion controls access from the second host computer to data stored in the second storage areas and transmission of the copy of data stored in the second storage areas to the fourth storage system via the fifth communication line, in which the second and the fourth storage areas are formed as a second pair relation, wherein the first control portion manages the first pair relation and the second pair relation as a first group, wherein the first control portion gains first status information of the first pair relation, issues a request of second status information of the second pair relation to the second storage system, gains the second status information from the second storage system, and holds the first status information and the second status information as group status information in the first memory, wherein the first control portion sends the group status information to the first host computer, when the first control portion receives a request of gaining the group status information from the first host computer, wherein the group status information is an information table in which status of each pair registered in a group is indicated by a number of pairs of each status, wherein said first host computer after gaining the group status information judges status of the first group by use of a decision table, said decision table stores information which indicates the status of a group and the group status information, which includes information concerning the number of pairs of each status, stored in corresponding relation to each other, and wherein processing for judging the status of the first group includes: extracting the first or second status information about each storage system and error information from the gained group status information; classifying the extracted status information about the storage systems according to their statuses and calculating a number of pairs in the same status; after the calculation, comparing the result of the calculation and the numbers of pairs of each status stored in the decision table; where the result of the comparison indicates that the status of the first group is not error, assigning the status indicated by the decision table where the result of the calculation and the number of pairs match as the status of the first group, and ending processing; and where error status which indicates a fault that occurs during copy is included in the extracted status information, referencing the group status information, identifying a storage system having the error information, gaining the error information of the storage system, displaying the error information including information which indicates the storage system in which a fault occurs, and ending processing.