Abstract: Inputting data necessary for designing an IT system leads a throughput evaluation part to draft a system idea meeting a design standard value for throughput and leads a reliability evaluation part to draft the system idea meeting a design standard value for failure probability. A cost evaluation part evaluates a cost of the system idea, while a cost judgment part judges whether there exists a system idea whose cost evaluated by the cost evaluation part is within an allowable range or not. When the cost judgment part judges that there is no system idea, a reconfiguration part reconfigures the design standard value for throughput, the design standard value for failure probability, and the allowable range of cost in the input data part, and the reconfiguration part carries out calculations repeatedly until there can be drafted a system idea whose cost is within the allowable range.

Abstract: A system includes an input unit (2) to which failure information corresponding to failure modes of constituents indicating software and hardware, a system configuration information and a standard value of system availability are inputted, a producing unit (32) producing a fault tree based on the system configuration information, a calculating unit (34) calculating unavailability corresponding to the failure modes based on a result of analyzing the failure information, and calculating system availability based on the calculated unavailability and the fault tree, a determining unit (35) determining whether the system availability meets the standard value, an extracting unit (36) extracting a basic event related to an increase in the system availability when the system availability is determined to be below the standard value, and resetting units (38, 39) resetting new unavailability and the like based on whether it is possible to reduce the unavailability of the extracted basic event.

Abstract: A system includes an input unit (2) to which failure information corresponding to failure modes of constituents indicating software and hardware, a system configuration information and a standard value of system availability are inputted, a producing unit (32) producing a fault tree based on the system configuration information, a calculating unit (34) calculating unavailability corresponding to the failure modes based on a result of analyzing the failure information, and calculating system availability based on the calculated unavailability and the fault tree, a determining unit (35) determining whether the system availability meets the standard value, an extracting unit (36) extracting a basic event related to an increase in the system availability when the system availability is determined to be below the standard value, and resetting units (38, 39) resetting new unavailability and the like based on whether it is possible to reduce the unavailability of the extracted basic event.

Abstract: Inputting data necessary for designing an IT system leads a throughput evaluation part to draft a system idea meeting a design standard value for throughput and leads a reliability evaluation part to draft the system idea meeting a design standard value for failure probability. A cost evaluation part evaluates a cost of the system idea, while a cost judgment part judges whether there exists a system idea whose cost evaluated by the cost evaluation part is within an allowable range or not. When the cost judgment part judges that there is no system idea, a reconfiguration part reconfigures the design standard value for throughput, the design standard value for failure probability, and the allowable range of cost in the input data part, and the reconfiguration part carries out calculations repeatedly until there can be drafted a system idea whose cost is within the allowable range.