Abstract: In a method of producing a data replica, data processing requests are issued from application programs running in application servers. Data processing corresponding to each of the data processing requests is executed in each of database servers, and a result of the data processing is replied as a response to one of the application programs which has issued the data processing request. The supply of the data processing requests to the database servers is controlled to keep the process order of the requests between the database servers.

Abstract: Operation information to a DBMS issued from an application (3102) operating on a primary system (3100) to middleware (3103) is acquired by acquiring means (3105) and transmitted to a backup system (3200) through a communication channel (3300) by transmitting means (3108). In the backup system (3200), the received operation information is modified by modifying means (3206) so that the operation information is suitable for the DBMS (3222) of the backup system, reproduced by reproducing means (3205), and issued to the DBMS (3222) of the backup system. With this, similarly to the data in a storage (3123) of the primary system (3100), the data in a storage (3223) of the backup system (3200) is processed, thereby realizing data multiplexing.

Abstract: A computer system is composed of a plurality of application servers each installed with an application program configured to issue data processing requests; and a plurality of database servers. Each of the database servers is composed of a storage, and installed with a database server middleware receiving the data processing requests and a DBMS managing data stored in the storage. Each of the data processing requests is duplicatedly forwarded to each of the database servers. The data processing requests received by the database middlewares are respectively assigned with sequence numbers uniquely defined over the whole of the computer system. The database server middleware converts the data processing requests received into corresponding DBMS-specific data processing requests, and forwards the DBMS-specific data processing requests in an order indicated by the sequence numbers.

Abstract: In a method of producing a data replica, data processing requests are issued from application programs running in application servers. Data processing corresponding to each of the data processing requests is executed in each of database servers, and a result of the data processing is replied as a response to one of the application programs which has issued the data processing request. The supply of the data processing requests to the database servers is controlled to keep the process order of the requests between the database servers.